122 THE MITOCHONDUIAL CONSTITUENTS OF PROTOPLASM. 



of the so-called "hatonnets" of Heidenhain, which resemble mitochondria in some 

 respects but differ altogether in others (Policard, 1910, p. 225). In many cases 

 it is hard to tell to which investigators refer. The "batonnets" have been known 

 for years, and much careful work was done on their possible relation to secre- 

 tion before the more elusive mitochondria were discovered. Another difficulty is 

 encountered in establishing a normal from which to work. Analogy is a pitfall 

 here, because there are such marked differences in the kidneys of different forms. 

 Certain snakes and amphibians are good material because the cells, unlike those 

 of adult mammals, contain characteristic secretion granulations like other glands. 

 Above all it is necessary to distinguish sharply between physiological changes and 

 pathological lesions; the latter will be considered on page 137. 



Benda (1903, p. 127) makes no reference to any relationship between the 

 mitochondria and the formation of secretion except to suggest that by contrac- 

 tion they draw the proximal and distal ends of the cell nearer together and thus aid 

 in the expulsion of the secretion. To this Policard (1905, p. 382) rightly objects. 

 Modrakowski (1903, j). 230), at an earlier date, described definite changes in the 

 Altmann's granules (mitochondria) in experimental diuresis and suggests that they 

 may act as condensers in the formation of secretion, but his illustrations do not 

 show them. The distinctive features of mitochondria in the different segments of 

 the urinary tubules have been studied by Regaud (1908c, p. 1145) and others. 



Regaud (1909f, p. 1035) was the first to claim that the mitochondria play a 

 definite part in the formation of the secretion. He worked with the kidneys of 

 snakes and found that where the mitochondria are abundant the secretion granules 

 are few, and vice versa. He records the gradual formation of the secretion granules 

 in the substance of the mitochondria in precisely the same way as in the salivary 

 glands. 



Policard (1910, ]). 272), however, working with the frog, after experimenting 

 in many ways, remarks on the fixity of the mitochondria and describes no marked 

 variations in them depending upon the quantity and character of the urine, though 

 they respond very readily by fragmentation to ]3athological changes. He has 

 described also (1912c, p. 450) the transformation of nutochondria into certain 

 granulations of unknown nature in the developing human kidney. Fahr (1914, 

 p. 120) has been able to stain secretion granulations and mitochondria differentially 

 in the rabbit's kidney and believes that there is no relation between them. 



More recently, Oliver (1916, p. 318) has studied the modifications which the 

 mitochondria undergo in experimental diuresis. The "batonnets" in the cells 

 of the proximal convoluted tubules, where the urea is secreted, lose their rod-like 

 form and occur simply as rows of granules. 8he found that the urea also appears 

 in the form of granules wliich are likewise arranged in rows and suggests that the 

 secretion of urea is bj- means of the mitochondrial batonnets which act as condensers. 

 It may be remarked that the rows of urea granules do not necessarily correspond 

 with the rows of mitochondria; they may simply alternate with them. It may 

 also be worth while to inquire whether phosphatids, of which we believe mito- 



