160 THE MINUTE ANATOMISTS 



THE ANATOMY OF THE SILKWORM 



The treatise De Bomhyce (1669) was the first thorough 

 account of the structure of any insect. So laborious 

 did Malpighi find the work of dissecting a small animal, 

 with no help to the eyesight but a simple lens, that he 

 safiered afterwards from an inflammation of the eyes. 

 In spite of this trouble, his delight in the new structures 

 which revealed themselves to him was so great that he 

 could not tell it in words. He was the first to observe 

 the air-tubes and spiracles of an insect, the many-cham- 

 bered heart, the silk-glands, the Malpighian glands 

 (named after him), the gangliated nerve-cord, the repro- 

 ductive organs and the development of the wings and 

 legs of the moth. He demonstrated experimentally the 

 function of the spiracles, showing that when silkworms 

 are placed in hot water many air-bubbles are given off 

 from these openings, and that when they are smeared 

 with oil the insect dies "in the time that one can say 

 the Lord's prayer." ^ He remarked the rhythmical con- 

 traction and dilatation of the last three segments of the 

 caterpillar, and doubtfully regards them as respiratory 

 movements, which they really are. 



The figure of the nervous system of the silkworm ^ 

 shows that Malpighi did not understand the brain, 

 which he divided into completely separated halves, nor 

 the relations of the oesophageal ring. The ventral 

 ganglia are too few, one being left out. It would be 

 rather like Malpighi to have drawn the nervous system 

 from a single dissection, and thus to have fallen into 

 errors which a less confident man would have easily 

 avoided. Swammerdam immediately detected these slips, 



^ Aristotle had taught that insects do not breathe, although he knew that 

 an insect dies at once when smeared with oil. 

 2 PI. VI, Fig. 2. 





