306 PROCEEDINGS OF THE ACADEMY OF [1887. 



formed from the entodermal layer of the inner mantle, the cells of 

 both being similar in every respect. The heart itself is composed 

 of a structureless basement membrane supporting a layer of striated 

 fusiform muscle cells. These "fibre cells" lie upon their flat sides, 

 with their long axes at right angles with the long axis of the heart. 

 They have a single oval nucleus and present a delicate transverse 

 striation (fig. 12.). They are much smaller than the fibres of 

 the trunk muscles. 



The Elctoblast (statoblast of Vogt.) situated on the central side of 

 the body near the cloacal opening consists in hardened specimens 

 of a mass of large irregularly polygonal bodies, showing no nuclei 

 and varying greatly in size. They are opaque and have a coarsely 

 granular appearance as if tilled with a sort of yolk material. They 

 are undoubtedly cells which have been greatly engorged and modified. 

 In sections they usually drop out to a large extent owing to the re- 

 moval of the oil and fat by the reagents, leaving a reticulum made 

 of the transparent connective material of the inner mantel in a cav- 

 ity of which, or rather on the outer side of which, the elseoblast lies ; 

 the entire mass being covered with the peculiar large plaster cells 

 previously described. 



The function of this body seems still to be undetermined. In ad- 

 ult specimens it disappears entirely, but is present both in solitary 

 and chain Salpce Avhen young. Vogt held it to be homologous with 

 the placenta, Salensky^ considers that in those Salpce developed from 

 the egg it arises from the same elements out of which the blood cor- 

 puscles and muscles are formed ("amoeboid follicular cells") ; in the 

 chain Salpce it is developed from the mesoderm. 



The Nerve Ganglion or brain presents a nearly spherical mass 

 covered with a delicate membrane which seems continuous with the 

 outer sheath of the nerve trunks. Upon section it shows an outer 

 layer of apolar ganglion cells, only the nuclei of which are to be 

 seen as a rule, and a central portion of lighter colored fibrillar 

 ("punct") substance (fig. 13, NG.). 



Resting upon the brain and in fact a continuation both of the cen- 

 tral fibrillar core and the external layer of ganglion cells, is the 

 Visual Organ of Salpa, (regarded by Huxley as an auditory organ.) 

 Outside of its nervous central ])ortion (fig. 13 vo) is a layer of rather 

 large cylinder cells (fig. 13 pc.) containing in their inner halves a 



1 Salensky (W.): "Uber die Entwickelungsgeschichte der Salpen" ia 

 Zeitschr. f. wiss. Zool. XXVII 1877. Moiphol. Jahrb. Ill p. 591. 



