104 



KANSAS UNIVERSITY SCIENCE BULLETIN. 



The gelatine solution is kept in test tubes that can be corked, 

 and when desired for use these are placed in a water bath. 

 The liquefied gelatine is then poured out on the slide and al- 

 lowed to harden for a few minutes. In order to make cells 

 suitable for mounting large objects, strips of glass are pressed 

 upon a slide in a manner indicated in the diagram. The 







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Fig.l 



liquefied gelatine is poured into the space in the center. 

 Within a few minutes after solidification, a hot needle is used 

 to melt small points in the gelatine into which the objects to 

 be mounted are then inserted. In this manner they can be 

 placed in any arrangement desired, and held in position with 

 the needle until the surrounding gelatine solidifies. 



It is thus possible to mount as many as fifteen or twenty 

 properly arranged frog eggs in different stages of segmenta- 

 tion. Care should be exercised to have the gelatine deep 

 enough in the cell to almost fill it up. After allowing the gela- 

 tine to cool to such a degree that all of the objects are held 

 firmly in place, gelatine heated barely enough to have a liquid 

 consistency, is then poured into the cell in sufficient quantity 

 to flood it, and a slightly warmed slide is placed upon the cell 

 in such a manner as to coincide in position with the slide below. 

 In preparing it, care must be exercised to prevent the in- 

 clusion of air bubbles in the cell, and at the same time furnish 

 a complete film of melted gelatine between the cover slide and 

 the underlying glass strips. This slide should be held in place 

 until the gelatine has solidified, thus holding it firmily in 

 position. 



It is next necessary to seal the mount. This is done by first 

 cleaning out the excess gelatine from the grooves formed by 

 the strips between the margins of the two slides and the edges 

 of the strips between them. This can be done with a small piece 

 of wood like a toothpick. Care should be taken to clean away 

 the gelatine quite thoroughly. It is even advisable to cleanse 



