THE SOCIAL LIFE OF THE LOWER ANIMALS. 529 
dated by different spermatozoids.* Though these transformations 
are to-day perfectly known and believed, yet naturalists quite often 
attribute the honor of this discovery to our confréres who have not 
known that the demonstration had been entirely made and that 
the new interpretation was generally accepted. But to return to 
our subject. Aid is thus as varied as we find in our own world: 
to one is furnished the domicile, to others the table,{ and to a cer- 
tain number a livelihood in lodgings.§ It is a complete system of 
lodging and subsistence, besides the best arranged philozoic institu- 
tion. But if on the part of these paupers, we see that they render 
each other mutual aid, we should not regard them as wholly para- 
sites or commensals. We believe we should be more just in calling 
them mutualists, and mutualism reclaims a place, as we have before 
said, by the side of commensalism and of parasitism. It will be 
necessary also to find a qualification for those which, as certain 
crustacea and even birds, are spongers or sharks || (des pique-assiette 
ou des écornifleurs) rather than parasites; and for others which 
pay for the aid rendered them by malicious deeds.{ _ 
And how shall we designate those which, like the little plover 
of which we have already spoken, render a service that we may 
compare to medical assistance ? 
The plover indeed acts as a dentist to the crocodile, as a small 
Species of frog acts as an accoucheur to his wife in using his 
fingers as forceps to bring forth the eggs into the world. And the 
beef-eater, does it not perform a surgical operation each time that 
it opens with its beak, the tumor on the back of the buffalo 
Which contains a larva? It is an operator who pays for his keeping. 
Nearer at home we see the starling render in our fields the same 
Service as the beef-eater i in Africa ; and can we not say that there is 
* Insects, Crustacea and worms furnish examples. An Isopod, Apseudes anomalus 
two forms of males; the ordinary, or the more common, resembles the R 
th e Cuma ve two sorts of males; the mor n also rather 
e female, and is found all the year, while the other is rarer, and only rs at cer- 
sag . We observe the same phenomena in several other Crustacea, 
oe i. ina , Cyprin 
ese observations have been made by Sars. cognized t 
orts of males and two sorts of females in Termes lucifuga —- e esi slike- 
Wise two sexual forms, the nereidian and the ——— 
the e ti a appe isa similar instance. 
stence of winter and summer r eggs in the same A 
t The Alepas and many others. The leeches. 
: The greater number of true parasites. l Piqui-beeuf et Milan parasite. 
T The ichneumons end by killing the larva which has given them life, after having 
e pad 
TURALIST, VOL. VIII. 34 
