48 ORIGINAL ARTICLES. 



Ill fact, the interior of the body is wholly occupied by two relatively 

 enormous organs — the double series of secretory cells, and the ovary. 



The former of these extends in a straight line from one end of the 

 body to the other, being attached at the extremities, but otherwise 

 lying loose in the interior. The cells lie side by side, and thus form a 

 double series. Some of them are very large indeed, being even as much 

 as Tr th of an inch in length by ^rd in breadth. Others, however, are 

 not above half as long, though they do not differ much in width. They 

 are not arranged with any regularity as to size, so that often a long one 

 lies by a short one, in which case, however, there is no gap; but the 

 series becomes more or less alternate, until, perhaps, another difference 

 brings each two cells again nearly opposite to one another. 



Each of the large cells contains a thick fluid, and about seven or 

 eight transparent nuclei, which are of tolerably even size, and about 

 T Q 8 y jj th of an inch in diameter. 



A very similar organ to this has been described by Meissner in 

 Mermis albicans, where also it consists of a double series of large cells, 

 with nuclei. The large cells, however, are full of oil globules, and the 

 nuclei contain crystals. In Mermis nigrescens and in Gordius the fat- 

 body consists of a large number of much smaller cells. In the last- 

 named genera this fat body is continuous, with a very short oesophagus ; 

 and I have therefore examined the two ends of it, to see whether the 

 same was true for Sphserularia. I never, however, found anything in 

 the least like the narrow oesophagus and peculiar stomachal sacs of 

 Mermis, nor the small mouth and short oesophagus of Gordius. It 

 seems, however, that this corpus adiposum must be considered as ho- 

 mologous with the intestine of the Nematodes, although no central 

 cavity has been formed in it. 



The ovary is about four inches and a half in length ; it commences 

 near one end of the body, as a fine tube about yoV o* n °^ an ^ ncn ^ n ^~ 

 ameter, and gradually increases to about y^th, after which it slightly 

 diminishes, then again expands into an uterus y\)th in diameter, and 

 then finally contracts to about g^th, and opens externally at the extre- 

 mity of the other end of the body. It lies perfectly free in the general 

 cavity, but near the vulva is connected with the large fat-cells. The 

 female generative organs of Sphserularia differ therefore considerably 

 from those of Mermis and Gordius, both of which have a double ovary 

 connected with the vulva by a short oviduct. 



According to Claparede,* in all Nematoidea, the Purkinjean vesicle 

 is the first-formed part of the egg : — 



" II parait certain," he says, " que chez tous les Nematoides la vesicule germinative 

 est l'element primaire de Toeuf. Le blastogene n'ayant chez VAscaris mucronata qu'une 

 largeur d'environ m, 013, ne peut comprendre plus que deux vesicules germinatives dans 

 sa largeur. Ces vesicules s'entourent d'une mince couche d'une substance glutineuse et 

 incolore. C'est la le premier rudiment du vitellus. Nous n'avons pas rencontre d'indi- 

 vidus chez lesquels les oeufs eussent attaint un developperaent plus considerable." 



De la Formation et de la Fecondation des CEufs chez les Vers Nematodes, p. 38. 



