DEVELOPMENT OF EYE OF SPARROW 319 



of the lacrimal gland is indicated by a group of blood-vessels 

 long before the gland cells appear. Blood-vessels also run 

 parallel to the path of the developing gland and duct. In fact, 

 the direction of growth is indicated by a richer blood supply. 

 The growing bud forms a more or less cylindrical bar of almost 

 uniform diameter which runs in a tortuous manner from the 

 conjunctiva to the region of the gland. Here it branches and 

 forms the four or five lobes of the gland. The gland increases 

 in size until the fifth or sixth day after hatching, when it has 

 reached almost the adult condition except in size. During this 

 time there has been a disintegration of the cells in the center of 

 the lobes of the gland and in the connection to the conjunctiva 

 which results in the formation of the lumen. It is now ready 

 to function. 



x\ccording to Kirchstein ('94), the lacrimal gland has not 

 reached its full development in the newborn child, being only 

 one-fourth to one-third as large as the adult gland. This has 

 been confirmed by Goez ('08). There is also a difference in the 

 appearance of the cells (Axenfeld, '99). It is claimed by De 

 Wecker ('99) and Baratz ('02) that, even though the lacrimal 

 gland is not completely developed at birth, it is nevertheless 

 capable of functioning. This condition corresponds favorably 

 to the development in the sparrow a few days after hatching, 

 when the eyes open. 



The development of the harderian gland is very similar to that 

 of the lacrimal. It makes its appearance at a slightly earlier 

 date. At seven and three-fourths days' incubation a solid 

 cylindrical bar of epithelial cells extends backward from the 

 conjunctival pouch, formed by the nictitating membrane and 

 the eyeball, to a short distance beyond the equator of the eye. 

 Its course is more direct and less tortuous than that of the 

 lacrimal gland. The diameter gradually increases with the 

 backward growth. This growth continues until, by the thir- 

 teenth day, it has reached almost as far as in the adult. It has 

 increased greatly in size, but as yet shows no lumen. The size 

 increases until, by the second day after hatching, it covers a 

 relatively large part of the proximal surface of the eyeball. 



