THE MITOCHONDRIAL CONSTITUENTS OF PROTOPLASM. 117 



having some of the reactions of the colloid substance. But he admits that his 

 observations are not sufficiently numerous to permit him to arrive at any definite 

 conclusion. It is difficult to conceive of the direct transformation of a phosphoUpin 

 into a compound containing relatively large quantities of iodine. 



Goetsch's (1916, p. 132) recent work on toxic adenomata of the thyroid gland 

 is of very great interest in this connection, for he found that there is a great 

 increase in the amount of mitochondria parallel with the appearance of the chnical 

 symptoms of hyperthyroidism. This may be interpreted by the adherents of the 

 transformation hypothesis to mean that the epithelium is secreting more rapidly, 

 that the mitochondria are increased in number for this reason, and that this is 

 evidence that they are actually transformed into the secretion, just as Grynfeltt 

 supposes. But this explanation is taking a good deal for granted. True, the 

 hyperthyroidism may be due to an increase in amount of a single secretion which 

 is produced normally, yet there is some evidence for the alternative assumption 

 that the thyroid secretion is polyvalent and not univalent. Moreover, it is possi- 

 ble that the symptoms of hyperthyroidism may result from an increased rate of 

 metabolism on the part of the thyroid epithelium and the consequent liberation in 

 excess of products of this heightened metabolism rather than of normal secretion. 



PARATHYROID SECRETION. 



The evidence in favor of the mitochondrial origin of tliis secretion is still less 

 satisfactory and convincing. Bobeau (1911, p. 186) bases his conclusion entirely 

 upon a correspondence in the distribution of the mitochondria and certain lipoid- 

 like droplets in the cells. He demonstrated the mitochondria by mitochondrial 

 methods which he does not specify and the Hpoid by the method of Ciaccio. He 

 assumes that the lijwid droplets constitute a precursor of the secretion, or rather 

 the secretion itself, and that they arise by a swelling-up of the mitochondria. 



CEREBROSPINAL FLUID. 



Though Hworostuchin (1911, p. 232) was the first investigator to supply us 

 with an accurate description of the mitochondria in the choroid plexus, it remained 

 for Grynfeltt and Euziere (1912, p. 64) to make an attempt to discover their rela- 

 tion to the formation of the cerebrospinal fluid. They found three types of cells 

 in the choroid plexus of mammals: (1) striated cells, containing many long fila- 

 mentous mitochondria generally running from the base of the cell toward its distal 

 portion; (2) vesicular cells, filled with small vesicles possessing clear centers sur- 

 rounded by a peripheral layer of stainable substance; (3) vacuolated cells, crowded 

 with droplets of variable dimensions. They concluded that these three represent 

 different stages in the same process of secretion. According to them the mito- 

 chondria enlarge to form the vesicles, the vesicles change into the vacuoles, and 

 the vacuoles discharge their contents into the ventricular system and thus form 

 the cerebrospinal fluid. 



PoUcard (1912e, p. 430), in a short paper iniblished only a few weeks later, 

 says that he is unable to accept this interpretation; for he is of the opinion that 

 we have to deal with two processes, not with one. He found all stages between 



