THE MITOCHONDRIAL CONSTITUENTS OF PROTOPLASM. 



75 



During cell division the mitochondria are distributed in much the same way 

 in plants as in animals. They persist during the whole process; they are absent in 

 the spindle area, whether a. definite spindle be formed or not; and they are divided 

 in approximately equal amounts between the two daughter-cells. But in minor 

 respects their distribution varies more in animals. I have reference, for instance, 

 to the mitochondrial palisade described by Benda (1902, p. 781) in Blaps, which 

 is (so far as I know) unknown in plants. In animal cells they are almost invariably 

 disposed in a radial fashion about the centrosome, but such a condition has, to the 

 best of my knowledge, not been described in plants. Tlois discrepancy may, 

 however, be due to the well-known absence of a typical centrosome in the angio- 

 sperms. Kingsbury (1912, p. 45) makes the interesting suggestion that (since 

 in the terms of Lillie's theory of cell division the centrosome is a negative center) 

 the mitochondria, being reducing substances, carry a positive charge and accumu- 

 late around the centro.some in order to discharge it. 



In the cells which are not dividing 

 the mitochondria sometimes heap up _, — ^k\ 



about the centrosome and sometimes do 

 not. Their behavior may indicate whether 

 the centrosome is active. 



Fig. 1. — Dividing cells in chick embrjo. Fig. 2. — Meristem and young and old cortical cells of the |iea. 



A-E in mitosis and f-j in apparent amitosis. showing primary diffuse arrangement of mitochondria (a), 



secondary condensation about the nucleus (b), and final 

 even distribution throughout the cytoplasm (c). (.Wter 

 N. H. Cowdry.) 



Perinuclear condensations of mitochondria occur in both plants and animals. 

 In the early meristem of plants, generally, mitochondria are found indifferently 

 distributed in the protoplasm. They seem to approach and come in actual con- 

 tact with the nucleus, in which position they enlarge and form plasts which migrate 

 away from the nucleus and become distributed more or less evenly in the surround- 

 ing cytoplasm. Guilliermond has repeatedly described this migration and finds 

 that the mitochondria become more and more resistant to acetic acid during this 

 process of plast formation. Similarly, in the spermatogonia of certain animals 

 the mitochondria make their way to the nucleus and become so closely applied to 

 it that investigators have been deluded into thinking that they actually originate 



