96 CARNEGIE INSTITUTION OF WASHINGTON. 



ship of plant and animal mitochondria (chondriosomes), concerning 

 which there has been considerable difference of opinion in the literature, 

 has been studied by Mr. N. H. Cowdry. The author has approached 

 the problem from both its chemical and morphological aspects, includ- 

 ing new methods of technique in the form of supravital dyes of the 

 janus-green series, which had not previously been applied to plant 

 cells. He finds that, just as mitochondria are universally present in 

 animals, so do they occur in all plants, with the exception of some of 

 the lowest forms (myxomycetes and certain algae), and even in these 

 groups structures are present which may ultimately prove to be 

 mitochondrial. In their morphology the mitochondria are identical 

 in plants and animals, showing in the two species similar variations in 

 size and shape in the different tissues and different cells. Similar 

 fixatives preserve them, modify them, and destroy them in like manner 

 in plants and animals. Plant mitochondria react to the janus-green 

 test and stain with supravital dyes in substantially the same way as 

 animal mitochondria. It is, however, more difficult to obtain a good 

 coloration. Their composition, as indicated by solubility with respect 

 to acetic acid, heat, and other reagents, is subject to similar variations 

 in both. All points of comparison of mitochondria in plant and 

 animal cells thus bring to light a striking degree of similarity. One 

 must conclude that this general similarity and wide occurrence are an 

 indication that mitochondria are an essential constituent of living 

 matter. 



In studying the chondriosomes in the testicle cells of Fundulus, 

 Professor J. Duesberg has followed a subject of especial interest because 

 of the possible role these structures may play in heredity. He finds 

 that in the cells lining the distal part of the excretory ducts the chon- 

 driosomes are represented by long chondrioconts whose arrangement 

 reminds one of Heidenhain's or Pfliiger's rods. In the proximal part 

 of the excretory ducts the chondriosomes are replaced by granules of 

 pigment. The connective tissue of the testicle contains a number of 

 cells with special protoplasmic structures — bacillus-shaped chondrio- 

 conts and secretion granules, and these are probably to be regarded 

 as interstitial cells. Chondriosomes are found in all generations of 

 germ-cells and are transmitted during mitosis from one generation to 

 the next. Coarse and irregular in shape in the spermatogonia, they 

 become equal in size and spherical in the spermatocytes. Their 

 number is obviously reduced during the period of maturation; in the 

 young spermatid it can be estimated at eight or thereabouts, and 

 finally, in the ripe spermatozoon, it is reduced to three, evidently as 

 the result of fusion of the granules and condensation of their substance. 

 The chondriosomes are located at the posterior part of the head and 

 consequently close to the origin of the tail. The various stages of the 

 spermatogenesis of this form are illustrated in Professor Duesberg's 

 paper. 



