50 OEIGINAL ARTICLES. 



The young animals are born soon after the eggs are laid. They are 

 about -gTjth of an inch in length, and grV o^ n ^ n diameter at the broadest 

 part. They are very active ; the skin has the appearance of being ringed. 

 The head is pointed; the tail ends more abruptly, and makes a sudden 

 curve. The anterior end of the body is transparent; but the rest is 

 darkened by minute, round, strongly-refracting globules. As soon as 

 the Humble Bees come out in spring, young Sphgerulari may be found 

 together with old ones, in some of them. I have met with them from 

 the beginning of May till the middle of July, and the whole abdominal 

 cavity of the humble bee often swarms with these little worms. In 

 order to ascertain roughly what the number might be, I washed out 

 the inside of a bee, and then collected all the young Sphgerulari to- 

 gether. I then put them into a measuring bottle, and after shaking 

 up, poured away half of the contents. Repeating this process, until 

 only about a hundred were left, it was easy to calculate what the num- 

 ber must have been, if half had been removed a given number of times, 

 though, of course, no great accuracy was thus obtainable. I repeated 

 this experiment rive times, and thence concluded that one specimen 

 contained about fifty thousand young Sphgerulari, three about sixty 

 thousand, and one even over a hundred thousand ! It seems almost in- 

 conceivable that a bee should live with such an immense number of pa- 

 rasites in its body ; and still more so, that it should, meanwhile, go 

 about its daily duties as if nothing was the matter. 



These experiments, however, give but a faint idea of the number 

 of young to which a single female Sphaerularia might give birth. In every 

 case the whole ovary was full of eggs, in various stages of development; 

 and, considering the minuteness of the eggs, and the size of the ovary, 

 the number present must be enormous. If the young worms can in 

 any manner leave the bee without destroying it, there seems no reason 

 why nearly all of these should not succesively come to maturity, and be 

 hatched ; but, even supposing that this is not the case, and that in the 

 preceding experiment I have ascertained the greatest, or nearly the 

 greatest number of young Sphgerulari which can be produced in a 

 single bee, still the chances against any one of them attaining to matu- 

 rity must be very great ; for it is evident that if the sexes of a given 

 species are equal in number, and if the species is neither increasing nor 

 diminishing, the chances against any given young one attaining to ma- 

 turity may be obtained by halving the average number of young ones 

 produced by each female. 



It would seem, at first sight, that the history of the young Sphae- 

 rularia was very simple. "We might suppose that the infected bees 

 would die in their nests; and that the young worms would then leave 

 them, and immediately eat their way into other bees. This view would 

 also be supported by the fact, that, at least as far as my experience 

 goes, each infected bee contains, on an average, five or six Sphgerulari. 

 Two reasons, however, inconsistent though they may appear, mili- 

 tate against this supposition. The first is, that too large a propor- 

 tion of the youug Sphgerulari would live ; and the second is, that the 



