268 THE JOURNAL OF INDIAN BOTANY. 



In plants, some of the mitochondria remain "inactive," that is, retain per- 

 manently their original form, while others develop into (1) amyloplasts, (2) 

 chromoplasts, and (3) chloroplasts. This fact has led many investigators to 

 conclude that the primordia of plastids are really not mitochondria at all, but 

 are structures of an entirely different order. Such a view finds its strongest 

 support in Cryptogams having one or few large chloroplasts, as in Conjugatae, 

 Anthoceros, and Selaginella ; here the primordia of plastids are distinguished 

 by their larger size, even in the youngest cells of the growing points. Guilli- 

 ermond is convinced that such a distinction should not be made, because the 

 staining and other reactions of plastid primordia are exactly those of 

 " inactive '' mitochondria, and even the size distinction disappears in Phanero- 

 gams and in fungi. He thinks that the most that can be said is that there are 

 two kinds of mitochondria in the plant cell. 



The function of " inactive " mitochondria is not known, though in animals 

 where no other kind exists, they are believed by some authors to elaborate 

 secretions and certain pigments, to play a part in oxidations, and to function 

 in some way in heredity. Probably they have similar functions in plants. 



Microsomes are more or less transient, minute, fat-like granules, variable 

 in number, and distinguished in various ways from mitochondria. Nothing 

 beyond the fact of their existence is mentioned ; it is not even known whether 

 they are of general occurrence in plant cells. 



The vacuole system is a constant feature of plant cells, and arises in 

 young cells from " vacuole primordia " lying close to the nucleus. These 

 primordia so closely resemble mitochondria in appearance that some cytolo- 

 gists hold that they actually are mitochondria. They possess about the 

 same fixing and staining reactions, but are distinguished in various ways. 

 The author believes that absolutely no relation exists between the vacuole 



system and the mitochondria that they are two quite independent 



systems superposed on each other in the cell. The primordia enlarge as the 

 cell grows, they anastomose to form a network, and portions swell up to 

 become the familiar vacuole system. The process of growth appears to be 

 the result of hydration of the original substance of the primordia. The 

 vacuoles probably are centres of elaboration of various substances, e.g., 

 anthocyanins. 



The paper is fully illustrated by figures from various authors, and a 

 complete bibliography is given ; one is struck by the preponderance of 

 papers in French. The author very skillfully emphasizes the deficiencies 

 in our knowledge of cell morphology, and shows the need for an immense 

 amount of the most detailed and painstaking investigation. 



Winfield Dudgeon. 



Physiology 



Hahn, Glenn G„ Hartley, Carl and Rhoades, Arthur S. Hyper- 

 trcphied Lenticels on the Roots of Conifers and their Relation to 

 Moisture and Aeration. Jour. Ag. Bes. 20 ; 253 — 265, 1920. 



The authors observed warty excrescences on the roots of conifers, parti- 

 cularly Pinus ponderosa, as they were dug for shipment from a nursery in 

 Nebraska. Microscopic examination reveals the fact that they are enlarged 

 lenticels. Further search revealed such growths on the roots of twenty-one 



