322 ANNUAL OF SCIENTIFIC DISCOVERY. 



a very prominent knob, which is entiivly wantinp: in tho fomalo 

 and yoiin^. Tliis same fish has a most oxtraonlinary mode of 

 icprodiu'tion. The egjjs pass — I don't know how — into the 

 iimnlh, tlie Ijottom of which thoy cover, between th(! internal 

 uppcndajjes of tlie l)raiu lii;e, ami especially in a jjocket, i'ormed 

 liy the superior pharynirians, which they completely fill. There 

 they are hatched, and the young, free of their shell, continue to 

 grow until they are in a tit state to take care of tluMuselvcs, I 

 don't know how long this takes, but I have already met with 

 examples, in which the young were uo longer provided with the 

 vitelline sac." 



Decrees of Domestication. — There are in animals three I'ccog- 

 ni/ed and distinct degrees of capacity for domestication. The first 

 cla<s are animals of a " domesticated nature," being those which, 

 when once thoroughly domesticated, continue habitually with man, 

 will not willingly leave him, and, if they do so accidentally, will 

 )ii-ol)al)iy return ; among these are cows, horses, sheep, and poultry. 

 The second are animals capable of only an imperfect domestica- 

 tion. They breed freely in the homestead, and are useful to man ; 

 but, if they escape from him, will proI)ably not return; among 

 these are tamed deer, hawks and pheasants bred at home, and gold 

 and silver fish in i)rivate waters. A third class, sometimes called 

 domesticated, such as hares, raijbits, monkeys, parrots, canaries, 

 etc., is altogether incapable of domestication ; for, whatever aa 

 eccentric meml)er of tiie species might do, they will, as a rule, 

 cseape to savage life at the first opportunity, unless coerced by 

 climate or hunger. Some species require to be semi-domesticated 

 for centuries, before they become completely so. Without atten- 

 tion to these distinctions, experiments in domestication are liable 

 to be failures, or only partially successful. 



AnimalUij of Sponges. — Pi"of. H. J. Clark, in " Silliman's Jour- 

 nal"' for November, 1866, communicates a paper on the animality 

 of the ciliate sponges, which he regards as belonging to the Pro- 

 tozoa. He examines specially the marine species Leucosolenia 

 (Grantia) botri/oides, Bowerbank. lie concludes as follows: 

 " What are the diversities of other genera of the Spongiae ciliatae 

 I cannot more than conjecture ; but seeing that one of the genera 

 is so closely related to the monociliate Flayellata, it can hardly be 

 possible that the othei's ai"e very far removed ; and I shall feel 

 warranted, therefore, in assuming, ujjon the premises, tiiat the 

 whole group of Spongice ciliatce is as intimately allied with the 

 monociliate Infusoria Flagellata as is possible for it to be without 

 actually constituting, with the latter, a uniform family." 



Temperature of Birds. — Dr. Davy has a paper on this subject in 

 the " Proceedings Royal Society," No. 78. He thinks that the res- 

 piration of birds is less active than is commonly supposed, and that 

 their high temperature is maintained by their warm clothing, and 

 by the small loss of heat they experience through pulmonary or 

 cutaneous e vai^oration . 



Muscular Power of Insects. — M. Felix Plateau has made many 

 experiments on the muscular force exerted by insects. By attach- 

 ing d wire to the legs of insects, he ascertains the weight they 



