414 MODELS FROM SERIAL SECTIONS [Ch. XI 



material obtainable in the open market which would be more suit- 

 able and more generally available. 



Blotting paper seemed promising, and an actual trial showed it 

 to be admirably adapted for the purpose. Since maldng the first 

 model in 1905 it has been constantly used in the laboratory of embry- 

 ology in Cornell University. Models made from it were demon- 

 strated before the Association of American Anatomists in 1905 and 

 before the International Congress of Zoology in 1907. 



"The advantages of blotting-paper models are the ease and cleanli- 

 ness of their production and the Ughtness and durabihty of the prod- 

 uct. The models are broken with dif&culty, are easily packed or 

 transported, and when they cleave apart are easily repaired, thus 

 contrasting with the weight and fragility of wax models and their 

 deformation by heat." 



"By this process are secured for the original model reconstructed 

 from microscopic sections the same quahties which have made the 

 Auzoux models molded from papier-mache such useful and last- 

 ing additions to laboratory equipment; and, in the hands of Dr. 

 Dwight and Mr. Emerton, of Harvard University, have aided so 

 much in the demonstration of structure and form of special anatomic 

 preparations." 



§ 669. Thickness of blotting paper. — Blotting paper of a uniform 

 thickness of i mm., tVram., and ^ mm. was found in the market. 

 The I mm. is known as 140 lb. A. and costs about two cents for a 

 sheet 61 X 48 centimeters (24 X 19 in.). 



The thickness is easily tested by cutting out 50 small pieces, pihng 

 them, dipping one end in melted paraflSn, and pressing them together. 

 The whole pile should of course measure 50 mm. if the paper is milli- 

 meter paper (§ 669a). 



§ 669a. — Book-stores, paper dealers and job printers are supplied by the 

 paper manufacturers with samples of blotting paper. One can look these 

 samples over, select and order the kinds desired. The millimeter blotting 

 paper mentioned in the text is one of the cheaper grades, costing by the pack- 

 age of 500 sheets about two cents a sheet (sheets 61 X48 centimeters, 24 x 19 

 inches). 



§ 670. Size of the modeL — In deciding upon the size of the model 

 to be made from a given series of sections one shoiild select the largest 



