220 CORA J. BECKWITH 



at any time during the growth-period or cleavage, as suggested 

 by Duesberg ('10) and Faure-Fremiet ('10 a). Their origin and 

 behavior in Hydractinia indicate that they may be either preco- 

 ciously differentiated portions of the protoplasm (Vedjovsky' 07) 

 or metaplasmic bodies. 



Scepticism as to the identity of the bodies described as plasmo- 

 somes, chondriosomes, chromidia, ergastroplasm, etc., has been 

 expressed by a number of observers (Veratti '09, Penas '11, 

 Lundegard '10, Gurwitsch '10 and others) who believe that they 

 have nothing in common but their name. Such an impression 

 is certainly gained in reviewing the literature. The experiments 

 with staining tests lead the writer to join these investigators in 

 the belief that structures which have the same staining reactions 

 may have been confused. If the standard tests for mitochondria 

 are to be relied on for identifying them, then the mitochondria of 

 Hydractinia, which respond to these tests, do not conform in 

 many respects to the conditions found in other forms. 



IV. MATURATION PHENOMENA AND AMITOSIS IN HYDRACTINIA 

 AND EUDENDRIUM 



When this work was begun it was my purpose to re-examine 

 the eggs of several Hydroids which had been described as showing 

 no mitotic figures during maturation, a nuclear disintegration or 

 fragmentation occuring at the time of the disappearance of the 

 germinal vesicle. The suggestion was made ''that reduction 

 phenomena of maturation may well be accomplished without 

 any of the complex and spectacular processes of mitosis" (Hargitt 

 '06). Nuclear reconstruction was described as occurring later 

 through the collection of these fragments in several 'nuclear 

 nests' throughout the egg (C. W. Hargitt, Pennaria, '04, Euden- 

 drium '04, Clava '06; Allen, Tubularia crocea, '00); and the 

 cleavage of the egg as frequently amitotic. Smallwood ('09) 

 and G. T.' Hargitt ('09), have since established the occurrence of 

 typical maturation phenomena and mitotic cleavage in Pennaria 

 and Tubularia, while independent studies by the writer ('09) 

 gave the same result both in Pennaria and in Clava. Since 



