No. 515] NOTES AND LITERATURE 



a morphological without a corresponding physiological individ- 

 uality. If such an individuality is implied it is a queer kind 

 of individuality, or would be for any other bodies than chromo- 

 somes. But chromosomes have had so many queer things 

 attributed to them that queerness with them has almost ceased 

 to be queer. 



In a third paper ("The Relation of the Nucleolus to the 

 Chromosomes in the primary Oocyte of Asterias forbsii") the 

 same author expresses the belief that "all the hereditary ele- 

 ments are persistently held by the chromosomes . . . and that 

 these merely receive nutritive material from the nucleolus." 

 It may be granted that the figures and descriptions presented 

 show material to be transferred from the nucleolus to the 

 chromosomes. What the evidence is that this material is all 

 nutritive and none of it hereditary would be extremely impor- 

 tant. Certainly no such evidence is presented in this paper. 



The fourth paper that contains cytologieal matter is **The 

 Habits and Early Development of Linerges mercunus," by 

 E. G. Conklin. The egg of this medusa presents concentric 

 layers, the outermost of which is protoplasm nearly free from 

 yolk. As in the eggs of various other ecelenterates, cell-division, 

 at least the first division, begins in this peripheral layer; but 

 contrary to what has been held for some other species, the 

 nuclei and chromosomes are here somewhat distant from the 

 point at which the first visible changes toward division occur. 

 There seems, consequently, no observational ground for suppos- 

 ing that this outer layer does not actually start up the division. 

 This would appear to be a very significant point. Conklin gets 

 no evidence that cell-division is ever amitotic in this species as 

 it has been reported to be in one or two other ecelenterates. 



Normal Development: W. K. Brooks and B. McGlone show 

 ("The Origin of the Lung of Ampullaria") that in the pul- 

 monale studied, the lung seems to be quite a different structure 

 from that of other pulmonates and hence the conclusion is 

 reached that "there is no reason to think that there is any an- 

 cestral connection or relation between the lung of Ampullaria 

 and that of the pulminates." In the paper by Conklin noted 

 under cytology, it is shown that gastrulation in the medusa 

 studied usually takes place by invagination, but sometimes by 

 the immigration of a mass of endoderm cells at the vegetal pole, 

 and the author remarks on the close relationship between the 



