22 ANIMAL PHYSIOLOGY. 



directions. ID the web of the frog's foot, and in other trans- 

 parent textures capable of being examined microscopically 

 in living animals, they have been seen not only changing 

 their shapa but even moving about, so that they may well 

 be termed amoeboid. In the fine interstices between other 

 tissues, nuclei are often seen in great abundance in homo- 

 geneous matrix, without any apparent protoplasm about 

 them. 



It may be here mentioned, that to bring delicate textural 

 elements such as connective-tissue-corpuscles into view under 

 the microscope, many niceties of method are resorted to, and 

 among these there are some points which deserve special 

 attention. The material should be perfectly fresh, and not 

 allowed to come in contact with water, as water swells up 

 and destroys delicate corpuscles. Spirit, on the other hand, 

 shrivels textures. By using serum and various weak solu- 

 tions, these deleterious effects are avoided. Principal among 

 preservative substances, weak solutions of chromic acid and 

 bichromate of potash may be mentioned, to which spirit may 

 be daily added in small quantities. "Water added to specimens 

 previously treated with chromic acid no longer destroys the 

 corpuscles. In examining nucleated corpuscles, staining with 

 an ammoniacal solution of carmine is often of the greatest 

 service : the specimen should be washed after being stained, 

 and should then be put up for the microscope in glycerine. 

 Yery often the beauty of the specimen is greatly increased 

 by addition, after glycerine, of a little nitric acid. This 

 must, however, be carefully washed away again, before it has 

 had time to destroy the carmine staining. 



10. White Fibrous Tissue. The term connective tissue 

 is a very general one, and the varieties to which we have 

 already referred are the homogeneous and areolar; but there 

 are others which are more markedly fibrous, and constitute 

 the group of white fibrous tissues, namely, fascia, aponeurosis, 

 tendon, and ligament. 



Fascia is the name given to strong, felted arrangements of 

 white fibrous tissue spread out in sheets. An aponeurosis 

 is a sheet of white fibrous tissue arranged in parallel fasciculi, 

 or in two or more sets of decussating fasciculi, and having in 

 consequence a shining appearance. Tendon is white fibrous 



