86 RECORD OF CURRENT RESEARCHES RELATING TO 



walls of which are formed by a thin layer of longitudinal muscles, a 

 thicker layer of circular fibres, and a cylindrical ciliated epithelium ; 

 the pharynx is short, and the remaining portions of the enteron may 

 be broken up into three parts ; in addition to these there may be made 

 out a " Nebendarm " altogether similar to the structure found in 

 Bonellia, and described by Eolando as a " vaisseau que longe I'intes- 

 tin." Just before the anus there are two brown tubes (anal vesicles), 

 which are provided with a number of ciliated infundibula, and are 

 lined by a flattened epithelium, devoid of cilia, and filled with a brown 

 pigment. The so-called segmental organs form two pairs of thin- 

 walled tubes, which are connected with the coelom by a ciliated infun- 

 dibulum, and often to the exterior by a short efferent canal. Brown 

 pigment-granules can be made out in the epithelium, and there are 

 two layers of muscular fibres, of which the inner has a longitudinal, 

 and the outer a circular direction. These organs also serve as 

 efferent ducts for the generative products. 



The vascular system is stated to consist of a dorsal and of a ventral 

 longitudinal vessel ; the former breaks up, at the hinder end of the 

 pharynx, into two branches, which embrace the enteric canal, and 

 unite on the ventral aspect, only, however, to again divide into two 

 vessels, which open into the ventral blood-canal. This latter also 

 gives rise to two anterior vessels, which open by a transverse vessel 

 into the dorsal blood-canal. No communication was observed between 

 the developed blood-vascular system and the ccelom. 



The generative products are developed in the hindermost region 

 of the ventral blood-vessel ; a whitish spot may be seen to consist of a 

 close aggregation of rounded cells with large, clear nuclei (" primitive 

 ova "). Balls of these cells, varying in size, break off and pass into 

 the coelom, where each cell continuing to grow separates the yolk mate- 

 rial from the protoplasm of the egg. In the male the cells do not 

 become free so soon ; the cells undergo continual division, and the 

 small nuclei are converted into the head of the spermatozoon, very 

 much as in Sipimculus. 



Natural History of the Orthonectida.* — This group t has now 

 been studied by Professor Elias Metschnikoff, who has had an oppor- 

 tunity of examining Bhopalura Giardi (sp. nov.) from the peritoneal 

 cavity of Amphiura squamata. The body of the parasite is irregularly 

 pyriform, and was found attached to the viscera of its host. On 

 examination rounded protoplasmic diverticula may be seen, which 

 best call to mind the blunt processes of the Ehizopoda. At first sight 

 veritable Protozoa, they are seen to be more differentiated owing to 

 the constant presence of ova in their bodies ; these ova form small 

 rounded cells, with a clear and only slightly granular contents, pro- 

 vided with a large nucleus, and with a nucleolus. They are the so- 

 called " endodermal " cells of Giard ; exhibiting a regular division, they 

 give rise to a blastula, in the cavity of which a few cells are to be 

 observed ; these are the indications of a bilaminate condition. The 

 tubes in which the genel^tive products are developed are either male 



* 'Zool. Auzeiger,' ii. (1879) p. 547- 

 t See this Journal, ii. (1879) p. 886. . 



