12 GENETICS 



or statoblasts, is thus essentially maintained. The 

 bryozoan colonies of two successive seasons in a fresh- 

 water pond may be regarded as parts of the same 

 identical colony, since they present an "organic resem- 

 blance based on descent," although the sole representa- 

 tives of the parent colony during midwinter may be the 

 sparks of life locked up within the statoblasts buried 

 in the mud. 



Similarly, the asexual spores of many plants, such 

 as molds, mosses and ferns, may be regarded as gem- 

 mules reduced to the lowest terms, namely, to single 

 cells. As in the preceding cases so in this instance the 

 resemblance of the offspring which may arise from these 

 spores, to the parents which produced them, is due to 

 the essential material identity of two generations. 



These illustrations of heredity in its simplest mani- 

 festations give the key to "organic resemblance" higher 

 up in the scale. Sexual reproduction is no less plainly 

 the direct continuation of life though in this instance 

 two sporelike fragments out of one generation con- 

 tribute to form the new individual of the next genera- 

 tion instead of one fragment. In all cases there is a 

 material contmmty between succeeding generations. 

 Offspring become thus an extension of a single parent, 

 or of two parents, while heredity is simply "organic 

 resemblance based on descent." 



5. SOMATOPLASM AND GERMPLASM 



In forms that reproduce sexually there occurs a 

 differentiation of the body substance into what Weis- 

 mann terms somatoplasm and germplasm. 



