478 Prof. A. B. Macallum. Detection and Localisation 



a reaction for " masked " iron, and thus in muscle this element and 

 phosphorus would seem to have the same distribution. 



The matrix of cartilage in Menobranchus and the frog gives a 

 marked reaction for phosphorus, which seems in large part to be due 

 to inorganic phosphates, for it appears soon after the addition of the 

 nitric- molybdate reagent. The reaction in some specimens appears 

 in areas or zones about cartilage cells or groups of them, the areas 

 being separated by narrow zones in which no reaction was observed. 



In the maturing and mature ovarian ova of Amphibia the cyto- 

 plasm is very rich in organic phosphorus, though not so much so as 

 the nucleus. As the yolk spherules form, the amount of phosphorus- 

 holding substance seems to lessen, possibly through its being taken 

 up by the spherules which, even when freed from traces of lecithin, 

 give a marked phospho-molybdate reaction in about six hours. It is 

 to be noted that these spherules are also iron-holding. 



In the spermatozoids of Ascaris the organic phosphorus is, on 

 the whole, distributed as I have found the " masked " iron to be in 

 these structures.* The " nucleus " gave a deep phospho-molybdate 

 reaction, and a less marked reaction was obtained in the surround- 

 ing cytoplasm. 



A diffuse but distinct reaction for phosphorus was obtained in 

 human chorionic villi of the seventeenth (?) day, and in the pla- 

 cental villi of the sixth week and third and sixth months. A 

 part of this reaction is due to inorganic phosphates, for it is 

 obtained to a certain extent in about ten minutes after the nitric- 

 molybdic reagent is added. The cat's placenta is very rich in 

 inorganic phosphates distributed throughout the tissue, but more 

 abundant in the deeper portions of the organ. 



The colloid bodies of the thyroid are phosphorus-holding accord- 

 ing to Gourlay,t who relied in his experiments on Lilienfeld and 

 Monti's interpretation of the action of pyrogallol on the phospho- 

 molybdate compound. Through the kindness of Dr. J. H. Elliott, 

 I obtained an abundance of free colloid bodies of the ox, fixed in 

 alcohol, which, after extracting the lecithin, I fused in a platinum 

 cup with crystals of pure potassic nitrate. The mass, treated with 

 a quantity of the nitric-mo lybdate solution, became yellowish, 

 owing to the formation of the phospho-molybdate, the character- 

 istic crystals of which could be found under the microscope. The 

 reaction was not due to inorganic phosphates, for when thin sec- 

 tions of the ox's thyroid, freed from lecithin, were placed in the 

 reagent, the phospho-molybdate compound formed very slowly, and 

 the maximum reaction appeared only after eight hours. The pre- 

 sence of organic phosphorus in these elements does not, as Gourlay 

 * ' Quart. Journ. Micr. Sci.,' vol. 38, p. 229. 

 f Op. cit. 



