
LIFE-HISTORIES AND THEIR LESSONS, 203 

to undergo up to the time of their contraction into a chrysalis state, 
while Ogalina is hatched from Distoma eggs.”* And he further 
asserts that Colpoda and Paramecium “are the brood of 
Planariz !” f 
It is not difficult to explain these egregious errors of observation 
now. But it would be scarcely just to a distinguished, if philo- 
sophically narrow, Biologist, that these errors of the long past 
should be quoted as his latest judgments and most matured obser- 
vations. It is not less a matter of moment that Mr. Carter’s 
important emendations of his earlier observations should be noticed 
and receive their due weight. 
I called attention some time ago to an interesting observation 
made on the Tardigrades.t It will be instructive to quote from 
this. “Most microscopists have at some time made the acquaint- 
ance with the water-bears of the ponds, and a good many have 
followed their development. Whoever has done the latter has 
fully convinced himself of the truth of the statements of Holliker, 
Frey, Doytre, Kaufmann, and others, that the tardigrades in 
every instance produce large fecundated eggs, from which young, 
closely resembling the parents, emerge. Another feature of the 
tardigrades is the extreme hardness and toughness of their ‘skin.’ 
It is, in point of fact, speaking relatively to the Arthropoda, almost 
a ‘shell.’ This skin, it is also well known, is ‘cast’ by the creature, 
and it forms, in the case of the female, a shelter or protection for 
her eggs. . 
“Now, Dr. Bastian tells us that the power of reproduction in 
these forms is not limited to the ‘rudimentary generative organ,’ 
because ‘ Dr. Gros tells us that the dead tardigrades may ultimately 
be resolved into specimens of Actinophrys, Perammata, or Arcel- 
line, and that these products may at different times be either all 
of one kind or intermixed with each other and with young tardi- 
grades! On the strength of this discovery we are presented with 
a drawing, which I reproduce. (Fig. 15 @.) The subscription 
which accompanies this is very suggestive. It runs thus, viz: 
‘Seven large germs, into which the total internal substance of the 
parent has become resolved, each of them being capable of 
developing into a tardigrade.’ Now, wherever there are plenty of 
tardigrades there will be found dead forms, with their internal 
structure unchanged, and others which are mere empty shells or 
skins. Some of these latter are, doubtless, ‘cast skins,’ but the 
dead water-bears, in a trough not very plentifully supplied with 
food, will soon be attacked by paramecia; and although the 

* Essay on Classification, Boston, 1857, p- 182, 
+ Lond. Ed., p. 112. 
+ Popular Science Review, vol. XV., 344. 
