CHLOROPHYCEAE 
177 
but the shading is unfavorable. Look where you find Sphagnum, 
Vaucheria, Alisma, Equisetum fluviatile, Utricularia, Typha, and 
Char a. Dr. Nieuwland reports that Pandorina, Eudorina and 
Gonium are commonly found in summer as constituents of the green 
scum on wallows in fields where pigs are kept. The flagellate, 
Euglena, is often associated with these forms. If you have a culture 
in the laboratory, do not throw it out when the culture disappears, 
because new coenobia are likely to develop from the oospores. 
For collecting, use “bolting cloth” or “bolting silk” of the finest 
mesh available. With a piece of thin cloth about 15 cm. square, 
laid over an ordinary coffee strainer, you can pour through about 
4 liters of water in a minute. In this way you will secure all the 
Volvox in about a barrel of water in half an hour. Eudorina may be 
collected in the same way. Smaller members of the Volvox family 
like Pandorina, Gonium, and Chlamydomonas are too small to be held 
by the cloth; but if material is very abundant, the water goes through 
faster than the organisms and you will soon have many times as 
much material in a bottle as you could get by dipping. Many 
small organisms are effectively collected in this way, even when they 
are so small that most of them pass through the cloth. 
Material of Volvox and all the Volvocaceae may be fixed in the 
corrosive sublimate-acetic mixture, used hot—85° C. If material is 
to be stained and mounted whole, use the aqueous mixture; if it is 
to be imbedded and cut, use the alcoholic. For mounting whole, 
stain in iron-alum haematoxylin, or in Magdala red and anilin blue, 
following the Venetian turpentine method. A few bits of broken 
cover-glass, placed among the colonies, will prevent crushing. 
Many fixing agents cause the protoplasmic connections between 
the cells to be withdrawn. Figure 36 A, showing the protoplasmic 
connections in nearly the living condition, was drawn from material 
fixed in the hot aqueous corrosive sublimate-acetic acid solution; 
B, fixed in a 1 per cent chromo-acetic solution, does not show the 
connections; C to E show details drawn from sections. 
For paraffin sections, the material, preferably in sufficient 
abundance to make a layer half an inch deep in the bottom of a bottle 
as large as one’s finger, is infiltrated with paraffin in the usual way. 
In imbedding, simply pour the contents of the bottle out so as to 
form a thin layer on a piece of glass. If material is so abundant 
that you can afford to lose some of it, simply cool the paraffin in 
