CELLULAR DEGENERATION AND FORMATION OF FIGMENT. 103 



Observations on Cellular Degeneration and the 

 Formation of Pigment in certain Hydroids. 



By 

 Ernest Warren, D.$c.(L<on«l.)> 



With Plate XII and Text-figs. 1-11. 



In the examination of hydroids collected on the eastern 

 coast of South Africa it has been noticed that, in the case of 

 certain species, black, or very dark brown, colonies occa- 

 sionally occur in addition to those of the usual pale horn or 

 yellowish-white tint. This black condition of some of the 

 colonies was first noticed in 1905, when local specimens of 

 Sertularia loculosa ^zt.s/i; from the Natal coast had been 

 collected, and in a description^ of the specimens the matter 

 was referred to in the following terms: "In the black variety 

 the endoderm is provided with dark brown, opaque, pear- 

 shaped masses. These are, doubtless, cells, but I have not 

 with certainty detected the nucleus. The colouring matter 

 may be very opaque and compact, but sometimes it is seen in 

 the form of granules." 



Subsequently a similar condition has been found in a 

 number of other species, and a careful histological examina- 

 tion has led to the conclusion that the development of the 

 pigment is the result of a disturbance in the physiological 

 functions. The phenomenon is not uncommon amono- South 

 African hydroids, and there is no reason to suppose that it is 

 in any way peculiar to them. 



1 ' Annals of the Natal Mus.,' vol. i, pt. 3, p. ,308, 1908. 



