94 



DEVELOPMENT OF CEREBRO-SPINAL SPACES IN PIG AND IN MAN. 



Below the first measurement no glycogen was demonstrated by the method em- 

 ployed; above the higher limit in only one instance (series No. 41) was glyocgen 

 found. This finding of a limited period in the embryonic life of a pig during which 

 glycogen occurs in the cells of the chorioid plexuses does not coincide with Gold- 

 mann's observations on the rat and mouse. Furthermore, it was found here that 

 in stages up to 100 mm. the glycogen was practically generally distributed through- 

 out all the cells of the chorioid plexus, occurring with great regularity in every villus 

 and cell. This general distribution was not found in the plexuses of embryos over 

 1 10 mm. in length ; in these more advanced stages the cells containing starch occurred 

 in clumps, giving a localized distribution. In the stages under 100 mm. the glyco- 

 gen was present in very large amount, as estimated histologically. As the stages 

 advanced the quantity of glycogen decreased rapidly. This great amount of starch 

 was present in the same stages in which the general distribution of the cells occurred. 



Occuirence of glycogen in the clwrioid plexuses of embryo pigs. 



Goldmann^ 20 ) pictures the glycogen as occurring throughout the cells of the 

 chorioid plexus in the form of globules of larger or smaller size. Some of these 

 globules may be seen even in the surrounding cerebro-spinal fluid. This general 

 intracellular disposition was observed in this series in specimens measuring 66 mm. 

 and over (fig. 95). Below this measurement the glycogen occurred practically 



