1883. 81 Tra7is. N. Y. Ac, Set. 



puzzled the scientific world for ages. All the motions of life are due 

 to the contraction and expansion of a reticulate structure, which is 

 common to all living things. How easily all the observed facts are 

 explained ! What an admirable machine the hmcsba is ! Perhaps 

 somebody will ask, by what means the reticulum itself is enabled to 

 extend and contract. I am not aware that any effort has yet been 

 made to solve this problem. Enough, that the movements we see are 

 explained upon mechanical principles. Like the thousands of persons 

 who are satisfied to understand mesmerism as animal magnetism, 

 and strange phenomena as due to electricity in the air, these gentle- 

 men present, in the name of science, an explanation that does not ex- 

 plain. 



The sources of error in microscopical observation are : i. Improper 

 illlumination. 2. Imperfect correction of the objectives. 3. Incorrect 

 focussing. The first source of error does not concern us in the case 

 under consideration, for no special niceties of illumination are required. 

 The second is of more consequence ; but, in order to eliminate it from 

 my own observations, I have used objectives which were either adjusted 

 by the makers and set in fixed mountings, so that their corrections 

 could not be changed, or else I have adjusted the lenses myself by the 

 use of suitable objectives, so that their correction was as perfect as pos- 

 sible. Finally, errors of focussing alone remain as the only ones which 

 cannot be absolutely eliminated. Yet these, in the special objects of 

 study, the amccba and the blood-cells, are of no consequence what- 

 ever ; for no experienced observer can be in doubt as to the exact focus 

 for a white blood-corpuscle. 



A few words now about the appearance of blood-corpuscles when 

 highly magnified. The red corpuscles, when examined in the serum, 

 are double concave disks. When lying fiat, in the focus of a good 

 objective, they appear to be quite homogeneous in structure ; the cen- 

 tral portion of the disk, owing to the concave shape, appearing slightly 

 darker than the rest. I am not aware that it is claimed that a reticu- 

 lum can be seen in the red corpuscles under such circumstances. To 

 demonstrate the net-work, it is necessary to use some reagent, and a 

 saturated solution of potassic bichromate, diluted with about an equal 

 volume of water, is recommended for the purpose. The addition of 

 such a solution to fresh blood produces a great change in the appear- 

 ance of the corpuscles. They become granular, and some of them 

 undergo slow changes of form, budding, etc., as Dr. Heitzmann has 

 described in his book, recently published. When the corpuscles begin 

 to become granular, there is a time when they present an appearance 

 of reticulation. But careful observation with high-powers fails to show 

 any connecting net-work. There is nothing but a breaking up of the 



