958 



Lepisosteus osseus — (Continued) 

 early development of, 311 

 formation of scale in, 564 

 reproductive and urinary ducts of, 799 

 ventral mesentery of, 859 

 Leplonema condition (of meiosis), 135 

 Leptotene stage of meiosis, 128, 135 

 Leuchtenberger, C, 126, 233 

 Lewis, F. T., 629, 764 

 Lewis, M. R., 701 

 Lewis, W. H., 305, 702, 717, 718, 720, 



721, 904 

 Leydig, cells of, 17 



and male sex hormone production, 25 

 LH (luteinizing) factor, and physiological 

 maturing of sperm, 43 

 as interstitial-cell-stimulating hormone, 



ICSH, 40 

 effects on follicle development, 72 

 LieberkiJhn, crypts of, 620 

 Ligament, suspensory, anterior, 9 

 Ligamentum arteriosum, 930 

 Light, as a factor in reproduction, in Eu- 

 ropean starling, Sternus vulgaris, 

 44, 45 

 in ferret, 44 

 reflection of, and skin color, 592 

 Light spot, of Amhy stoma egg, 305 

 Lillie, F. R., theory of fertilization, 269 



{see also 320, 577, 794, 891) 

 Lillie, R. F., 286 



Lillie, R. S., theory of fertilization, 271 

 Limax cainpestris, formation of polar bod- 

 ies in, 214 

 Limb, extrinsic mass of premuscle tissue of, 

 721 

 intrinsic mass of muscle-forming mesen- 

 chyme of, 721 

 Limb-bud f^eld, in urodele, Ainby stoma 



unctatum, 509 

 Limiting membrane, external, of neural 

 tube, 817 

 internal, of neural tube, 817 

 Lineback, P. E., 628. 631 

 Lipoblasts, 664 

 Lipochromes, and affect upon skin color in 



the fowl, 592 

 Lipocytes, 664 

 Lipogenesis, 664 

 Lipophores, 591 

 Liposome, 664 

 Lips, formation of, 616 

 Liquor folliculi, of mature Graafian folli- 

 cle, 71, 74 

 Liver, development of, 736 

 in human embryo, 626 

 histogenesis of, 626 

 Liver cords, 626, 627 



Liver rudiment, development of, 623, 625 

 Liver-septum transversum complex, 861, 



863 

 Liver trabeculae, 736 

 Lobules, of testis, 793 

 Local origin theory, of primitive blood ves- 

 sel development, 730, 731 

 Locy, W. A., 536, 645, 645. 646, 648 

 Loeb, J., theory of fertilization, 268 

 Long bones, of appendages, development 



of, 692 

 Lophodont teeth, 607 

 LTH, leuteotrophin, 79 

 Lumbar (sacral) enlargement, of spinal 



cord, 821 

 Lumen, ovulatory, in Tilapia macrocephala, 



59 

 Lungs, 636 



cellular composition of, 649 

 development of, 642, 644 

 mammalian, alveoli of, 650 



formation of respiratory area of, 649 

 relationships of, 643 

 Lung pipes (parabronchi), 647 

 Lunglessness, 651 

 Luteal phase, of female reproductive cycle, 



93 

 Lutein cells, 85 



Luteinization factor (hormone) (LH; 

 ICSH), and release of sperm 

 from Sertoli cells, 43 

 and sperm development, 41 

 and spermatogenesis, 40-41 

 effect on testis activity, 40 

 response to, of seminiferous tubules, 

 24-25 

 Luteotrophin. LTH, 79, 103 



as involved in functional behavior of cor- 

 pus luteum in progesterone secre- 

 tion, 91 

 Luther, W., 441 

 Lymph, relation of to connective tissues, 



654 

 Lymph fluid, 726 

 Lymph hearts, 726, 747, 762 

 Lymph nodes, 726, 766 



formation of, 766 

 Lymph sacs, 764 



Lymphatic structures, development of, 764 

 Lymphatic system, 726 

 development of, 762 

 Lymphatic vessels, 726 

 Lymphoblasts, 733, 736, 766 

 Lymphocytes, 736, 766 

 Lymphoid forms, of blood cells, 736 

 Lynn, W. G., 878, 879, 886 

 Lysis, secretions which cause, during fer- 

 tilization, 229 



