. Adventures with animals and plants. Biology. 488 Organisms Are Products of Heredity and Environjnent unit ix. Fig. 437 Sentinel Fine, Yosemite National Park. Its one-sided growth is caused by wind. If seeds front this tree were planted in a sheltered valley how would the new trees look? Would Lamarck have agreed with your answer? Explain, (u. s. depart- ment OF interior) less well developed in the offspring. In other words he believed that acqiiired characters are inherited, even if only to a very slight degree. Do you agree with Larmarck? Do Exercises 6 and 7. Weismann's beliefs. Almost a c
. Adventures with animals and plants. Biology. 488 Organisms Are Products of Heredity and Environjnent unit ix. Fig. 437 Sentinel Fine, Yosemite National Park. Its one-sided growth is caused by wind. If seeds front this tree were planted in a sheltered valley how would the new trees look? Would Lamarck have agreed with your answer? Explain, (u. s. depart- ment OF interior) less well developed in the offspring. In other words he believed that acqiiired characters are inherited, even if only to a very slight degree. Do you agree with Larmarck? Do Exercises 6 and 7. Weismann's beliefs. Almost a century after Lamarck, a German biologist Au- gust Weismann (1834-1914) called at- tention to this important fact: as the fer- tilized tg^ (germ plasm) develops into a new individual it produces both soma- toplasm (tissue cells) and more germ plasm (primary sex cells which later form gametes). The diagram, Figure 438, should make this clear. Since this goes on in every generation, germ plasm is passed on in an unbroken line. If the animal should die without having reproduced, that particular germ plasm dies off and that line is broken. But under nonnal conditions the animal does reproduce and the germ plasm is immortal; it is continued from generation to genera- tion. Weismann spoke of this as "the con- tinuity of germ ; Strictly speaking. then, offspring do not really come from their parents; they come from the germ plasm carried within the soma or body of the parents. Since, according to Weismann, the fertilized q^^ produces both somato- plasm (tissue cells) and more germ plasm (primary sex cells), it follows that the primary sex cells are not made by the body which houses them; they come directly from the line of germ plasm car- ried from earlier ancestors through the parents. Examine the diagram again. Weismann believed that the sharp dis- tinction bet\veen germ plasm and soma- toplasm held for all organisms. But you read earlier that while it does hold for t
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