36 Motion of the Heart and Blood 



the chick in ovo, however, you will find at first no more 

 than a vesicle or auricle, or pulsating drop of blood ; it 

 is only by and by, when the development has made 

 some progress, that the heart is fashioned : even so in 

 certain animals not destined to attain to the highest 

 perfection in their organization, such as bees, wasps, 

 snails, shrimps, crayfish, &c., we only find a certain 

 pulsating vesicle, like a sort of red or white palpitating 

 point, as the beginning or principle of their life. 



We have a small shrimp in these countries, which 

 is taken in the Thames and in the sea, the whole of 

 whose body is transparent ; this creature, placed in a 

 little water, has frequently afforded myself and particular 

 friends an opportunity of observing the motions of the 

 heart with the greatest distinctness, the external parts 

 of the body presenting no obstacle to our view, but 

 the heart being perceived as though it had been seen 

 through a window. 



I have also observed the first rudiments of the chick 

 in the course of the fourth or fifth day of the incubation, 

 in the guise of a little cloud, the shell having been 

 removed and the egg immersed in clear tepid water. 

 In the midst of the cloudlet in question there was a 

 bloody point so small that it disappeared during the 

 contraction and escaped the sight, but in the relaxation 

 it reappeared again, red and like the point of a pin ; so 

 that betwixt the visible and invisible, betwixt being and 

 not being, as it were, it gave by its pulses a kind of 

 representation of the commencement of life. 1 



1 [At the period Harvey indicates, a rudimentary auricle and ventricle 

 exist, but are so transparent that unless with certain precautions their 

 parietes cannot be seen. The filling and emptying of them, therefore, 

 give the appearance of a speck of blood alternately appearing and 

 disappearing.] 



