32 [April, 



and white man, produce a hybrid offspring, and that hybrid reproducing in turn, 

 one or other of the original types will sometimes occur in such projieny. 



In Peru some Spanish families, two or three centuries since, intermarried 

 with the Inca, or purely Indian race ; and notwithstanding no further cross with 

 the Indian stock has subsequently occurred in these families, the Indian charac- 

 teristics are said occasionally to reappear even at the present time. 



Asiatics may have landed ages ago upon this continent ; but if they did so, 

 they have all been swallowed up and lost, in the indigenous population; and no 

 unequivocal trace of them remains in our Indian population. Before the landing 

 of Columbus, as well as since, the New World has presented every possible vicis- 

 situde of climate which could be supposed to produce a negro or any other race, 

 but not an individual of such a race has ever appeared. 



Dr. M. added, that such was the effect of the blending of dissimilar types on 

 the American continent, that he could produce, from among the colored population 

 of this city, many of the diversified forms and colours that exist in Africa itself. 

 In the case of seven species of domestic fowl, Temminck has shown that five 

 out of the seven cross among each other, a,nd produce prolific hybrids, and 

 then branch out into innumerable varieties: and the varieties of the domestic 

 pigeon differ more among each other than some distinct genera of other animals. 



Domestic cattle if bred in and in, dwindle. In Paraguay it is necessary to re- 

 fresh the stock by importations from other pastures. Other domestic cattle also 

 exhibit this peculiarity of hybrids. 



If mulattoes were bred in and in, without reporting fo the parent stock, they 

 would soon become extinct. 



A circular was read from the Committee of reception of thie National 

 Pacific Rail Road Convention, now in session in Philadelphia, asking 

 permission of the Academy for the members of the Convention to visit 

 the Museum} whereupon a resolution was adopted granting the desired 

 permission. 



A-pril mh. 



Dr. MortoNj President, in the Chair. 



Dr. Leidy remarked that crystalline bodies had been detected in most of the 

 tissues of many plants, but that their occurrence in animal tissues v/as much 

 more rare. The deposit of earthy salts in many tissues, such as bone, enamel 

 and shell, though analogous, was not homologous with crystallization. The earthy 

 deposit in the shell of the egg of many animals is probably an instance of true 

 crystallization within an animal tissue, for in those animals which have eggs with 

 a semi-membranous shell, as many helices, &c., we can detect the carbonate of 

 lime deposited in the form of regular rhombohedrons. He stated that he lately 

 met with a remarkable instance of crystallization within animal organic cells. 

 In examining the stomach of the larva of Arctia Isabella, a Lepidopterous insect, 

 he found that the nucleus of every epithelial cell contained an octohedral crystal, 

 the axes of which measured about the l-3750th of an inch. The cells were color- 

 less, (not white,) containing some faintly granular matter, which, in many in- 

 stances, was collected into distinct rounded masses. The nuclei were round. 



