W. COLE ON A PARASITE OF HUMBLE BEES. 99 



the ovary, containing only the germinal vesicle, np to the mature 

 egg enfolding the fully-formed embryo just preparing to wriggle 

 into its little world, in a snug corner of the bee's body. Tbe 

 growth of tbe egg is considerably advanced before it issues from 

 the vulva, but the embryo is not then formed ; after the egg is laid, 

 however, the development proceeds with great rapidity, and the 

 young are soon hatched out. They are exceedingly active in their 

 movements, thus presenting a marked contrast to their quiescent 

 mother. They vary, of course, somewhat in size according to their 

 age, but do not grow much in this stage of their existence ; the 

 bulk of those found in May and June are about gV^h °f an mcn 

 long, with a nearly uniform diameter of about x^oo^ u °f an mcn - 

 The end, which for the sake of distinction may be called the " head," 

 is somewhat pointed ; but the "tail" is very different, being blunt, 

 curved, and club-like. The structure of the young Sphcerularia is 

 of the simplest nature possible. Under a ^th inch glass the skin 

 is seen to be very delicately ringed. The interior of the body is 

 rilled, excepting a short, clear space before the head, with a 

 great number of small refractive globules, mixed with opaque 

 granules. By careful focussing, a faint line or notch can be dis- 

 cerned at the anterior end of the body ; but not the slightest 

 appearance of digestive or other organs can be traced. 



It is scarcely necessary to mention that all the large individuals 

 we have been considering are females ; but we now come to the 

 most curious fact connected with the morphology of this bee- 

 worm. Near the extremity of each female, at the end farthest 

 from the vulva, may be noticed a minute nematoid worm, which 

 might readily, at first sight, be passed over as one of the young, 

 did not certain peculiarities of form and its invariable presence in 

 the same position negative such a supposition. This little creature 

 is very transparent,, and perfectly motionless; it is about aV u 

 an inch in length, and T oVoth an inch in breadth. It may easily 

 be distinguished from the young Sphcendarice by the differently- 

 shaped "tail," which is sharply pointed, and quite unlike the 

 clubbed extremity peculiar to them ; the " head" is also somewhat 

 more truncate, and the little notch more clearly defined. The skin 

 is likewise ringed, but the stria? are coarser, and more easy to make 

 out ; other characters, whether histological or anatomical, are, how- 

 ever, equally conspicuous by their absence. The body is filled 

 with granules and globules similar in appearance to those found in 



