186 THE AMEBIC AN MONTHLY [October, 



set more distinct than the other. Fig. 12 represents a group of seven ; Fig. 

 13 also a group of seven, but not all in the same plane as was the case in Fig. 

 12. Fig. 14 represents a group of seven, but unlike Fig. 13 in that the entire 

 group is surrounded by a cell-wall as was the case in Fig. 5. 



A number of different forms have been purposely drawn ; many others 

 could be found and w^ould show either modifications of the forms already de- 

 tailed, or perhaps some new departures. In many cases more than seven 

 cells could be found. Now is there any deeper fact indicated by these group- 

 ings ? They are every one of them in accord with the law which governs the 

 mode of multiplication in this plant. In yeast it is found that multiplication 

 takes place by budding. A small pimple at one place increases in size until 

 it rivals the size of the cell from which it grew. In Protococcus, growth 

 takes place by division. First the spherical cell acquires an oval shape. 

 Then the nucleus divides and the content forms into two parts. A new cell- 

 wall forms across the oval. Later, the old cell-wall indents ; this forms a 

 constriction which grows deeper and deeper, as in Fig. 2 and Fig. 3. While 

 this constriction grows deeper, the two-cell contents each undergo a second 

 process of division and begin the formation of four cells out of two. This 

 may take place in one cell first and give a three-celled group (e. ^., Fig. 6- 

 Fig. 8), or it may take place in both at once (Figures 7, 9, 10, 11). The 

 older the cells the deeper the constriction ; thus. Fig. 7 is older than Fig. 10 ; 

 in Fig. 7 the cells are nearly cut apart. The divisional planes may keep on 

 in the same plane and form groups like Fig. 12, or they may fall in different 

 directions and produce groups like Fig. 13. This law of division can be 

 traced out from the study of cells in different stages of division. There is a 

 second mode of division inside the original cell-wall called internal cell division, 

 of which two stages are seen in Fig. 5 and Fig. 14. It is much less common 

 than the other mode. 



A comjolete survey of the Protococcus plant would require a look at its 

 phvsiology. This we can only do very hastily. If some Protococcus were 

 put in pure rain-water it would grow and thrive there, provided it was kept in 

 the sunlight. If kept in the dark it would die. Yeast would live in the dark, 

 but not in pure rain-water. Protococcus has by virtue of the green coloring 

 matter a peculiar power. It can so direct the energy, which is sunlight, that 

 the woi-king part of the plant — the protoplasm — can use it to manufacture 

 its own food from the gases of the air and from pure rain-water. This power 

 does not belong to animals which depend for their food upon plants contain- 

 ing chlorophyl. We can see with the microscope enough to 'surprise and 

 delight us in the mere green dust on the bark of the tree ; but if we could 

 follow the work which is being done inside that minute cell while we are 

 looking at it (if we are working b}' da3-light), how much more would there 

 be to see ! We have by no means reached the end — only the beginning. 

 We could with reagents penetrate a little farther and demonstrate the chemi- 

 cal nature of cell-wall and cell-contents, but no one has yet had a peep into 

 the laboratory where sugar and albumen are compounded from insubstantial 

 ammonia, hydrogen, carbon-dioxyd, and water. 



Maceration fluid for molluscan nerve tissue is made, according to Bela 

 Haller, as follows: — 5 parts acetic acid, 5 parts glycerin, 20 parts distilled 

 water. Specimens, after soaking in this for 4-24 hours, are then teased in 

 50% glycerin, or washed and stained in picro-carmine or ammonia carmine. 



