292 



observed the reverse change in the development of the cilia of 

 the embryos of Siphonophora, and in the cellular elements of 

 the Sponges.^ When the cells of Magosphoera have become 

 amoeboid, they take on an encysted stage, and undergo a 

 cleavage, exactly like yelk-division ; rupturing the cyst, the 

 cleft mass comes out, consisting of an aggregate of cells which 

 develope flagella, and thus the original form is reproduced. 



Glycerine-jelly. — This appears to be an excellent medium 

 for preserving objects which Avill admit of a little ' clearing ' 

 action on the part of the glycerine. It is not so powerful in 

 this way as glycerine itself, and is far easier to use, setting 

 firmly. It is more ' clearing ' than Deane's jelly, and melts 

 at a somewhat lower temperature. We have found it very 

 useful for mounting worms of various kinds, especially 

 Annelids with the view of demonstrating the form of the 

 setse. Tliat which we have used was obtained from INIr. 

 Baker, of Holborn. We believe it Avill be found very useful 

 for a host of objects. The easiest way to use it, is to put a 

 small bit on the glass-slip, melt it over a lamp or near the 

 fire, then place in the object to be mounted and carefully lay 

 on the thin glass-cover. All is then over. 



A Method of Mounting delicate Tissues. — Dr. Macintosh, of 

 Murthley, whose beautiful book on Nemertean worms we 

 elsewhere notice has used the following method in preparing 

 and preserving sections of these Avorms for the purpose of 

 studying the tissues. He hardens in alcohol, and after 

 making sections carefully, washes in water. Superfluous 

 water being got rid of, a drop or two of a concentrated solu- 

 tion of the chloride of calcium is added and the cover-glass 

 immediately cemented down. No cell of any kind is used, 

 and some preparations have been kep)t thus for four years. 

 Those Avho know the delicacy^ of the tissues of Invertebrata 

 will highly value this method, which enables the observer to 

 retain his preparation unchanged by the too great clarifying 

 power of glyceri]ie or resins. 



Method of Staining and Mounting in use at Vienna.— The 

 section of tissue to be mounted is cut with a simple broad razor 

 (the large knives specially made are not to be recommended) 

 Avell covered with alcohol or water, as the case may be — the 

 tissue being embedded in a mixture of wax and oil poured into 

 a small paper tray if necessary. The section is then placed in 



' In the development, of the spermatozoa of the oligocha't Aunelii), 

 Tithifex, I liave observed a similar i)henomenon, and what is even more re- 

 markable, very large, active, fusiform masses, exhibiting very rapid move- 

 )nont like a ciliuni, and possessing at the same time the contractility of a 

 pseudopodium. — E. R. L. 



