Neo lamarckism

Neo lamarckism

Lamarck’s ‘theory of inhertitance’ was further studied by a group of
scientists. Their ideas supporting Lamarck’s opinion collectively constitute
neo Lamarckism.

The neo Lamarckians were of the opinion that ‘adaptions’ are
universal in nature. An adaptation happens through causal relationship of
structure, function and environment. Due to changes in the environment, habits
and life style of organism gets altered. Thus gradually the organism acquires
new structures. The newly obtained character gradually becomes an
inheritable trait. This opinion and argument is a modified form of
Lamarckism. These ideas stressed direct action of environment on organisms.
Support to neo-Lamarckian concept – Experiments (Neo lamarckism)

Neo Lamarckism

1. McDougall (1938) tried to prove that learning is an acquired character
that can be inherited. He did his experiments on rats.

He deviced a ‘T’ shaped tank. The tank had two exits. One exit was
well lighted. However at the terminal region of the exit he deviced an
arrangement for giving electrical shock. The pathway to the other exit was
kept dark. At the terminal exit point a small piece of cheese was kept as a
reward. McDougall dropped several rats into the tank. Many of the rats
preferred lighted pathway to escape and at the exit they received electric
shock. Those rats, that preferred dark pathway received the cheese. He
repeated the trial several times. Gradually many rats learnt the correct route
for escape. Subsequently the rats were allowed to breed and the next
generation developed.
The same experiment was repeated in the second generation. (Neo lamarckism)

According to Mc Dougall, it was claimed that the number of mistakes
committed, gradually got reduced. The speed of learning increased from generation to generation. Thus he concluded that learning is an acquired
character.

However later workers found some technical mistakes in the work
of Mc Dougall. The same experiment while repeated in other laboratories
failed to give similar results. (Neo lamarckism)

2. Temperature related changes in the body of mice was noted by F.B.Sumner
(1910). He reared one set of white mice in warmer temperature (20 – 300c)
and another set in cold conditions. He found that in warmer conditions the
mice developed larger ears and longer tails. He further claimed that these
characters were inherited.

Through similar works claim for inheritance of acquired characters
were made by Lindsey, Guyer and Smith and Kammerer. In all these works
while repeating, critics have found technical mistakes and rejected them
outright.

However, the controversy over ‘inheritance’ of acquired characters
still continues. This theory of Lamarck while has not been disproved totally,
it remains to be proved correct. (Neo lamarckism)

Related Topics in Zoology:

Bio Zoology All Important Topics

  1. Livestock and Management
  2. Important cattle breeds and their characteristics
  3. Milch breeds (or) Dairy breeds
  4. Dual purpose breeds & Draught breeds
  5. Exotic breeds of cattle
  6. Common diseases and control in Cattle – Contagious diseases
  7. Non-contagious diseases – Cattle
  8. Techniques adopted in cattle breeding
  9. Poultry Breeds
  10. Farming methods
  11. Poultry byproducts
  12. Fish Pond
  13. Edible Fishes Of Tamilnadu
  14. Medical Lab Techniques – Stethoscope
  15. Sphygmomanometer
  16. Haemocytometer
  17. Urine Sugar analysis
  18. ECG Electrocardiogram
  19. Computed Tomography CT
  20. Endoscopy (Laproscopy) techniques , Artificial Pacemaker
  21. Autoanalyser

Unit 7. THEORIES OF EVOLUTION Topic List Zoology

  1. Theories Of Evolution Introduction
  2. Lamarck Laws
  3. Neo Lamarckism
  4. Darwinism
  5. Theory of Natural Selection
  6. Objections to Darwinism
  7. Modern concept of Natural Selection

Comments

Post a Comment

Popular posts from this blog

Root Canal Treatment

Image
Root Canal Treatment Root Canal Treatment is a modern dental procedure to save a tooth in which the pulp (the living tissue within a tooth) has died or become untreatably diseased, usually as a result of extensive dental caries. Steps involved in Root Canal Treatment (1) A hole is drilled into the crown to remove all material from the pulp chamber. The root canals are then cleaned with fine-tipped instruments. The procedure is usually monitored by X-rays. (2) The cavity is washed out, and antibiotic paste and a temporary filling are packed into it. Some days later, the filling is removed and the canals are checked for sterlity. (3) When no infection can be detected, the cavity is filled with a sealing paste and/or tapering solid “point” made of gutta – percha resin mixed with zinc and bismuth oxides. The mouth of cavity is then sealed with cement. Related Topics in Zoology: Bio Zoology All Important Topics Human Physiology Introduction Nutrition Carbohydrates Poly hydroxyaldehydes...
Read more

Eye Infections and Eye Care

Image
Eye Infections and Eye Care Eye Infections 1. Stye A stye is an acute infection of the glands located at the eyelid margin. There is swelling, pain, itching and redness in a small area at the lid margin. Treatment consists of using frequent warm compresses on the eye. (Eye Infections) 2. Conjunctivitis: Infection in the conjuctiva is called conjunctivitis. Due to the infection the invisible blood vessels within the conjunctiva become engorged. Inflammation of the conjuctiva causes redness, discomfort and a discharge from the affected eye. The most common causes for conjunctivitis are infections (in children) and allergy (in adults). (Eye Infections) 2a. Infective conjunctivitis : Most conjunctival infection are caused by bacteria (e.g staphylococci) and are spread by hand-to-eye contact or by viruses associated with a cold, sore throat, or illness such as measles, viral conjunctivitis sometimes occurs in epidemics, spreading rapidly through schools and other groups. (Eye Infections) 2b...
Read more

Botanical description of Hibiscus rosa sinensis

Image
Botanical description of Hibiscus rosa sinensis Hibiscus rosa sinensis Botanical description of Hibiscus rosa sinensis Hibiscus rosa sinensis General Characters Habit Perennial shrub. Root Tap root system. Stem Aerial, erect, cylindrical, woody and branched. Leaf Simple, Alternate, petiolate, stipulate, serrate, glabrous, apex acuminate with multicostate reticulate venation. Inflorescence Solitary cyme and axillary. Flower Pedicel jointed, bracteate, bracteolate, bisexual, large, showy, pentamerous, dichlamydeous, actinomorphic, complete and hypogynous and mucilage is present in floral parts. Epicalyx 5 to 8 bracteoles outer to the calyx. They are green and free. Calyx Sepals 5, green, gamosepalous showing valvate aestivation and odd sepal is posterior in position. Corolla Petals 5, variously coloured, polypetalous but fused at the base and showing twisted aestivation. Androecium Numerous stamens, monadelphous, filaments are fused to form a staminal tube around the style. Staminal tube...
Read more