106 TUNICATA—SALPIANS CHAP. 
really belongs to the solitary stolon-bearing Salpa, which is 
therefore a female producing a series of males by asexual 
gemmation, and depositing in each of these an ovum, which will 
afterwards, when fertilised, develop in the body of the male into 
a solitary or female Salpa. This idea, if adopted, would pro- 
foundly modify our conception of Sa/pa as an example of a life- 
history showing alternation of generations, but it seems to me to 
give a distorted view of the 
sequence of events. The 
~) fact that the stolon while 
\ in the solitary Salpa con- 
tains, along with representa- 
tives of other important 
systems of the body, a row 
of germinal cells, does not 
constitute that solitary 
Salpa the parent of the ova 
which these germinal cells 
will afterwards become in 
the body of an independent 
bud. We must regard as 
the parent the body in 
which the ova become 
mature and fulfil their func- 
tion. The sexual or chain 
Fic. 66.—Salpa hexagona, Q. and G. Chain x 
form dissected from the left side. a, Anus ; Salpa, although really her- 
at, atrial aperture ; br, branchial aperture ; maphrodite in its life-his- 
d.l, dorsal lamina (“gill”); d.t, dorsal a : lly | E 
tubercle ; emb, embryos; end, endostyle ; tory » WW usually pr oto- 
m.b 2, m.b 7, second and seventh muscle- eynous, 1.e. the ova mature 
bands; 7.g, nerve-ganglion; v, visceral : : 
“nucleus.” (After Traustedt. ) at an earlier period than 
the male organ or testis. 
This prevents self-fertilisation. The ovum is presumably fertil- 
ised by the spermatozoa of an older Salpa belonging to another 
chain, and the embryo is far advanced in its development before 
the testis is formed. The development takes place inside the 
body of the parent, and is “ direct ”—no tailed larval form being 
produced. 
Development and Life-history——The segmentation of the 
egg is holoblastic, and gives rise to a number of blastomeres, 
= = i / 
fiom 
= 
1 According to Metcalf, Salpa cylindrica is protandrous. 
