217 



interspaces are those which take part in the development of 

 the other textures of Avhich the pia mater is constituted. 



In animals which hybernate, or Avhich have been kept 

 inactive in confinement for some time, and in man, under 

 similar circumstances, many of the red blood-corpuscles in 

 the blood-vessels are absorbed, just as they are from a clot 

 formed in any of the smaller vessels, and in some instances 

 from a clot situated external to the vessels, and the living 

 bioplasts (white blood-corpuscles) grow and multiply at their 

 expense. After a time such is the increase of the latter that 

 the capillaries in many tissues are almost entirely occupied 

 by them. This fact is illustrated by fig. 5, Plate XIII, which 

 represents very small capillary vessels of the mesentery of 

 the common frog in winter. The vessel is ahnost choked 

 up with white blood-corpuscles, only one or two red ones 

 remaining in the specimen from which the drawing was 

 taken. Another illustration of this fact is given in fig. 2, 

 Plate XI, which represents some of the capillaries from the 

 bladder of a half-starved frog. The capillaries have much 

 wasted, and contain no red blood-corpuscles whatever, their 

 cavity being entirely occupied with fluid liquor sanguinis 

 and masses of bioplasm, differing much in size, the largest 

 particles having the ordinary dimensions of the white blood- 

 corpuscles, while the smallest are so minute that they cannot 

 be demonstrated under a power magnifying much less than 

 1000 diameters. It is remarkable that in this case the white 

 blood-corpuscles are still growing and multiplying, and are, 

 indeed, probably the active agents in the absorption of the 

 tissues. In this specimen, from the most beautiful and deli- 

 cate of all the tissues of the frog, may also be seen the very 

 fine pale nerve-fibres, which I demonstrated some years ago. 

 A fine bundle is seen at a, from which point it may be readily 

 followed, as it divides into finer branches, ramifications of 

 which are seen in every part of the draAving. The bundles 

 of unstriped muscular fibres are marked b, while the bioplasm 

 masses of the connective tissue corpuscles are represented 

 here and there in the intervals. 



So far I have endeavoured to show that the masses of 

 germinal matter or bioplasm which are to be found in all parts 

 of the tissues and organs of man and the higher animals at every 

 period of life, and suspended in the nutrient fluids, notwith- 

 standing such remarkable differences in power, exhibit the 

 same general characters as those manifested by the living 

 matter of the lowest animals and plants. In all cases it is the 

 biojDlasm only which lives and grows. Moreover, attention 

 has been especially directed to the fact that the rate of growth. 



