TBANSACTIONS OF SECTION D. 793 



3. In order to see directly the canalisation of the cells under the microscope, 

 •we must use reagents capable of giving us a double stain. 



We cannot, however, make use of this method in all cases, for when the tissues 

 in which we wish to observe the protoplasm are living, reagents induce a contrac- 

 tion of the protoplasm into the cell-cavities and the rupture of the exceedingly fine 

 filaments which unite a cell to its fellows. To force, as it were, these filaments to 

 remain in position,! thought it desirable to produce a slow anoesthesis of the tissues 

 before fixing, hardening, cutting, and staining them. Osmic acid, which anatomists 

 often use, can be of no service to me, as it does not attack simultaneously the 

 various portions of the protoplasm surrounded by their cell-wall, and, moreover, 

 nearly always renders staining impossible at a later stage. I therefore had 

 recourse to true antesthetic agents, ether, chloroform, carbon disulphide, &c. 



The organism should be submitted in its entirety to the action of the vapours 

 of these reagents. When it has quite ' gone to sleep,' a fragment of the tissue 

 may be detached, plunged into alcohol containing picric acid, and then cut into 

 sections of ^J^ of a millimetre in thickness; if they are vegetable tissues, they 

 must be treated with dilute selenic acid, washed and double-stained. 



The cellular membranes, already much thinned out and partly destroyed by the 

 selenic acid, are seen to be coloured red, for instance, while the protoplasmic 

 filaments which pass through them are coloured blue, like the protoplasm of the 

 cell-cavities, and are seen to be in continuity therewith. 



This method has allowed me to ascertain that in highly oi-ganised species, such 

 as Dicotyledons, the protoplasm is continuous from the extremity of the roots to 

 the extremities of the leaves. The protoplasm is differentiated in these various 

 regions, and exhibits many various properties, but remains everywhere in a state of 

 continuity. 



4. It seemed to me that the method for photographing doubly coloured originals, 

 devised last year by MM. A. et L. Lumiere (of Lyon), would make this structure 

 easily visible. By photographing my preparations according to this method, I 

 have obtained examples on glass, showing the fine filaments of protoplasm coloured 

 blue clearly distinguished from the cell-wall membrane, which is coloured red. 



The following Demonstrations were exhibited in the Microscopical Room of the 

 Physiological Department from 2 to 4 : — 



1. Mr. Albert F. Calvert.— The Formation of Pearls. 



2. Mr. E. W. L. Holt.— Interesting British Food Fishes. 



3. Prof. M. Hartog.— Dividing Pollen Mother Cells. 



4. Dr. Carlier. — Iliberating Gland of Hedgehog. 



5. Mr. Goodchild. — Wings of Birds. 



6. Dr. G. Mann. — Embryo-sac of Angiosperms. 



7. Mr. A. C. Seward.— Structure of Myeloxylou. 



