MORPHOLOGY OF MITOCHONDRIA 123 



advances in microchemical tests, a more definite description of 

 the function of the Golgi apparatus will be given. 



MORPHOLOGY AND FUNCTION OF THE 



MITOCHONDRIA 



As the investigations of cytologists have been turned to the 

 form and function of the Golgi apparatus, so the mitochondria 

 have been neglected. It is a remarkable thing that so little is 

 known positively about one of the " best-known " protoplasmic 

 inclusions. Cowdry, in his summary of the knowledge of the 

 first-class mitochondria in 1924, had to admit that nothing of 

 importance was really known about them. 



A considerable mass of data has been collected so far regarding 

 the form and behaviour of these structures, but there does not 

 seem to be a sufficiently strong link to warrant any really general 

 statement concerning their function. There has been carried out 

 a very interesting and suggestive piece of work by Horning, which 

 will be described in detail below, which appears to make a definite 

 move in the right direction. We are still very far, however, from 

 being able to explain in terms of function such specialised behaviour 

 as the formation of the tail sheaths in many animal spermatozoa. 



The chemical nature of the riiitochondria appears to be some- 

 what similar to that of the Golgi apparatus, namely a protein sub- 

 stance compounded with a lipin. The micro-chemical reactions 

 of mitochondria are, however, not constant. This may be due 

 to the accumulation of deutoplasmic substances within them, 

 but there are several cases where the mitochondria do not appear 

 to stain typically, and these cannot at present be correlated with 

 any particular activity of such a kind. 



The general form of mitochondria has been well known for a 

 long time. They are usually filamentous, the length greatly 

 exceeding their thickness. In many cases, however, they show 

 that this is only one of many variations, the other extreme being 

 small spherical granules. Intermediate shapes are known, both 

 the filamentous and granular appearances occurring in the life- 

 history of one animal, or in the course of the cell cycle. Growth 



