INCLUSIONS IN EGG OF ECHINARACHNIUS 481 



of mitochondria in Hemiptera ('20) may be mentioned. He 

 states that the fact that the mitochondria are oriented with 

 definite relation to the centrosome proves that they are under its 

 directive influence, and therefore there is a mechanism for exact 

 division of mitochondria in mitosis as well as for chromosomes. 

 Since the flowing of material described by Chambers occurs at 

 this time, it is inevitable that any inert masses lying in the cyto- 

 plasm should be swept into Hne, and their orientation by this 

 means need have no connection with any attractive force exerted 

 on them by the centrosome. 



DISCUSSION 



All of the inclusions found in the egg of Echinarachnius parma 

 have been found in the unfertilized egg and they have decreased 

 during cleavage. This is wholly in accord with the nature of the 

 processes going on in the egg at this time. Its growth period is 

 past and it is about to start on a series of changes involving 

 great energy expenditure. While these changes are occurring 

 there is no opportimity for the aquisition of food material either 

 from maternal tissue or from the medium in which the cells are 

 living. All energy then must come from materials stored up 

 within the egg at the time it is set free from maternal tissues. 

 This does not in any way preclude transformations of some mate- 

 rials in the cytoplasm into others, and it is believed that such trans- 

 formations have been demonstrated. Here there are reduced to 

 their lowest terms the problems of the biochemist concerning 

 the synthesis of proteins, carbohydrates, and fats, for the large 

 amounts of the substances present in an animal body are merely 

 the sum total of all the minute particles of proteins, carbo- 

 hydrates, and fats synthesized and transformed in the single 

 cells. The exact steps in the synthesis of the complex chemical 

 compounds which serve as sources of energy in the physiology of 

 the cell are wholly undetermined. There are no reliable micro- 

 chemical tests for many of these substances and our interpreta- 

 tion of them according to their staining reactions may be quite 

 erroneous. 



