conditions undt'r wliirli such cases must arise. This swms lo 
me a suitable place, too, fijr inserting; a biolojjical remark. I have 
-spoken above of llic presence of fully developed^miricidia in lateral 
spilled eggs. If these eggs are unfertilized, as I hold they are. tbc) 
must be capable of deveioping by parthenogenesis \\> now see tk 
vital advantage the parasites would ilcrive from such a capability for 
the propagation of their race in localities where tlie conditions for 
infection are scarce. 1 may confess that from this point of viett tk 
hyqjothesis loses for me mucli of its original strangeness. 
I am now able to iin.swer the objection raised against mv 
interpretation of the lateral-spined eggs by IIOLCOMB. 1 suppose 
that tlie author means to say in his argument that the lateral-spined 
eggs could not have been derived from young females because in the 
course of the year during which tlie eggs were observed the females, 
though young perhaps initially, ought to have grown to se-xua! 
maturity and thus passed on to the formation of terminal-spineci 
eggs, in other words, during a year the eggs appearing in the faeces 
ought to have changed from the lateral-spined to tlie terminal-spined 
type. This objection of Holcomb would indeed hold good if the 
1 arzia eggs, like those of the intestinal parasites, were voided from 
ody of the host witliin 24 or 48 hours after their oviposition. But 
we know that they come from the liver, in whicli they have been 
J unfertilized females within a comparatively short 
P , ut from '^hicli they are voided as gradually as the terminal- 
spine eggs are from the bladder -quite irrespective of what has in 
the meantime become of the worms which laid them. The 
observation referred to by Holcomd is therefore no proof against 
voun^ ^'■P^'^tation that the lateral-spined eggs arc the products of 
young, or unfertilized, females. It is, on the contrary, an argument 
aJn t 
theTsL observed that the eggs changed 
the r slmpe .n a marked degree in so short a period. 
females it ®ffempts at independent wanderings on tlie part of the 
the hae’morrhoidlTXxus ofThT getting near 
"ermfectl ‘‘-o host may contract a 
previous infectioVare ttilTali^f “ 
m the liver. In both cases matters 
