160 



PROF. ST. GEORGE MIYAET ON 



rently incipiently segmented) form of many colonies (fig. 1, p. 138). 

 Multiplication of capsules by fission he believed to be general in 

 tlie compound kinds, and it seems to take place irregularly in 

 most species. In CollosphcBva, however, it can only take place in 

 the young shelless condition found in the middle of the colony, 

 since in the developed capsule the shell would hinder subdivision. 



Sometimes shells of Collosplicera are found in such a condition 

 as to indicate that they were formed while fission was in progress, 

 a shell sometimes appearing like two shells not quite divided off 

 one from another. 



Haeckel also found a Thalassoplaneta with two capsules within 

 it*, and doubted whether the circumstance might not be an in- 

 stance of the beginning of a colonyf ; but he decided against this 

 viewj, because of: — (1) the absence of alveoli, present in all known 

 compound forms ; (2) the presence of extracapsular pigment- 

 heaps (as in Aulacantha, Thalassicolla, and Coelodendrum) ; (3) the 

 presence of hollow spines, also present in the three genera last 

 named ; and (4) the finding of a single capsule dead. 



Most noteworthy is the fact that he saw § the contents of Collo- 

 zoum capsules break up into internal masses with oil-globules, one 

 in each, or with one large one in the middle of the divided masses. 

 This he considered as endogenous capsule-formation ; but (as we 

 shall see) it may have been an incipient stage of spore-formation. 



Haeckel also found oil-globules to be sometimes scattered in 

 the extracapsular sarcode, especially in small colonies in January 

 and February. 



In 1871, Cienkowski found || that the contents of the capsules 

 of CollosphcBra resolved themselves in twenty-four hours into 

 delicate vesicles, which again broke up into little spheroids 1[. 



In colonies the capsules of which are so filled, the corpuscles 

 collect together, the alveoli disappearing, and the contents of the 

 capsules begin to move and ultimately swim away as zoospores, 

 passing through the holes of the shell, the ripening, however, of 

 the different capsules not being synchronous. 



« L. c. pi. iii. fig. 10. 



t This circumstance, as well as the separate capsules of Sphcerozoum and Col- 

 lozoum sometimes found, much reduces the importance of the distinction be- 

 tween the single and compound conditions of Eadiolarian life. 



X L. c. p. 262. § L. c. p. 148. 



II Archiv f. mikrosk. Anat. vol. vii. p. 372 (1871). 



«jl Archiv f. mikrosk. Anat. vii. pi. xxix. figs. 5, 6, & 10, and ' Quarterly Journal 

 of Microscopical Science,' (new ser.) vol. si. pi. xviii. figs. 5, 6, & 8. 



