238 ANDREW JACKSON HOWE. 



slit up or removed, the organ is seen now to move, now to be at 

 rest ; there is a time when it moves, and a time when it is motion- 

 less. These things are more obvious in the colder animals, such as 

 toads, frogs, serpents, Hmall fishes, crabs, shrimps, snails, and shell- 

 fish. They also become more distinct in warm blooded animals, 

 such as the dog and the hog, if they be attentively noted when the 

 heart begins to flag, to move more slowly, and, as it were, to die ; the 

 movements then become slower and rarer, the pauses longer, by 

 which it is made much more easy to perceive and unravel what 

 the motions really are, and how they are performed. In the 

 pause, as in death, the heart is soft, flaccid, exhausted, lying, as it 

 were, at rest." 



To show that Harvey went to the foundation of 

 things, and left nothing to guess-work which could be 

 demonstrated, a few other quotations will be made : 



<; I have also observed that almost all animals have truly a 

 heart not the larger creatures only, and those that have red 

 blood, but the smaller and seemingly bloodless ones also, such as 

 slugs, snails, scallops, shrimps, crabs, crayfish and many others ; 

 nay, even in wasps, hornets and flies, I have, with the aid of a 

 magnifying glass, and at the upper part of what is called the tail, 

 both seen the heart pulsating myself, and shown it to many 

 others. If you turn to the production of the chick in ovo, how- 

 ever, 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 develop- 

 ment has made some progress, that the heart is fashioned; even 

 so in certain animals not destined to attain to the highest perfec- 

 tion in their organization, such as bees, wasps, snails, shrimps, 

 crayfish, etc., we only find a certain pulsating vesicle, like a sort 

 of red or white palpitating point, as the beginning or princi- 

 ple of their life. 



" We have a small shrimp in this country, which is taken in 

 the Thames and in the sea, the whole of whose body is transpar- 

 ent ; 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 



