Franklin P. Mall 351 



hours before cutting, the amount of endoplasm around the nucleus is 

 greatly increased, showing that by Mallory's method it becomes 

 , shrunken. x\s the embryo grows the endojDlasm increases in quantity 

 until in specimens 5 cm. long it forms a spindle-shaped mass around 

 the nucleus, the tips of which run out into the exoplasm and are lost. 

 Hajid in hand with the expansion of the exoplasm the endoplasm con- 

 tinues to grow until in embr^^os 10 to 13 cm. long it is ditl'erentiated 

 to correspond with that of the exoplasm. In the neighborhood of the 

 first white fibers the nuclei and endoplasm are arranged in rows, 

 while, where the exoplasm is changing into prefibrous tissue, they are 

 as before. More towards the epidermis the spindle-shaped endoplasm 

 is much larger, indicating that it is also active in the conversion of 

 exoplasm into prefibrous tissue. At this time the hairs are beginning 

 to develop and below their roots the nuclei are multiplying and accumu- 

 lating, apparently preparing much new endoplasm and exoplasm at 

 these points (Fig. 13). At any rate, in larger embryos (15-20 cm.), 

 there are islands of new syncytium at the roots of the embryonic hairs, 

 making it appear as if the soft syncytium is present at these points to 

 enable the hairs, in their further growth, to sink into the skin with 

 greater ease. In the rest of the skin the embryonic white fibers, the 

 prefibrous tissue, and fibrillated exoplasm are accompanied with 

 nuclei surrounded with a spindle-shaped mass of endoplasm, Not only 

 are all of these stages seen in the skin, but also between the radiations 

 of embryonic white fibers from the perimysium into the superficial 

 fascia. 



After the activity of the nuclei and endoplasm has produced enough 

 exoplasm to give rise to all the white fibers of the skin, which is the 

 case in embryos from 20 to 30 cm. long, they cease to be so prominent 

 and sink back into the form of irregular cells. Around the roots of the 

 hairs there are still the islands of quite typical sjmcytium. Probably in 

 both the scattered cells (nuclei and endoplasm) as well as in the islands 

 of syncytium we have forces which can develop new white fibers, should 

 circumstances so demand.'" The syncytium at the roots of tlie luiirs 

 undergoes a further differentiation in the development of elastic tissue, 

 v/hich I shall take up presently. 



It appears then that the connective-tissue syncytium grows rapidly 

 before it gives rise to white fibrous tissue. The nuclei multiply, the 



'i»Reddinghaus (Ziegler's Beitrage, 29, 1901) lias shown tbat in inflammation of the 

 omentum the fixed cells become active and form a syncytium which is in every 

 respect identical with the connective tissue syncytium of the embryo. His pictures 

 are in every respect like the normal specimens I obtained with Mallory's method. 



