970 



Pregnancy, determinative tests for, 108, 

 926 

 ectopic, and egg transport, 201 



Pregnancy cycle, in cow, 104 

 in sow, 102 



Pre-mandibular somite, in sharks, 716 



Pre-oral (head) gut, 482, 484 



Pre-oral pit, 502 



Pre-otic somites, as origin of eye muscles 

 in shark group, 716 



Prepuberal period, of post-embryonic de- 

 velopment, xiv 



Presphenoid portion, of sphenoid bone, 

 696 



Prevost, 281 



Price, G. C, 773 



Primary blastular condition, of fish blasto- 

 derm, 368 



Primary organizer, characteristics of, 399, 

 400, 401 (.see also Organization 

 center) 



Primary primordial germ cells, 117 



Primary tubes (tubulations), of primitive 

 vertebrate body, 456 



Primates, xxi 



Primitive knot (Hensen's node), formation 

 of in pig gastrula, 433 



Primitive plate, of reptilian blastoderm, 360 



Primitive streak, body of. formation of in 

 pig gastrula, 433 

 comparison with blastopore, 450 

 developing, 425 



development of in chick blastoderm, 420 

 formation of. cell movements in epiblast 

 involved in, 421 



Principal (chief) cells, of parathyroid 

 glands, 879 



Principal piece, of sperm flagellum, 149 



Principle, of presumptive organ-forming 

 areas of the blastula, 344 



Proboscidea, xx 



Process, ovulatory, 75 



Processus vaginalis, 6 



Procoracoid, 693 



Proctodaeal invagination, 485 



Proctodaeal membrane, 632 



Proctodaeum, 471. 482, 600 

 area of diverticulae of, 602 



Proestrus, definition of, 93 



Progestational phase, of female reproduc- 

 tive cycle, 93 



Progesterone, effect on ovulation, in the 

 hen, 80 

 effects of, 81, 91, 98 

 hormone of the corpus luteum, 85, 89 

 structural formula of, 91 



Progonal area, of genital ridge, 791 



Progonal support, for developing sex 



gland, 803 

 Projection, cephalic, and pre-chordal plate, 



in various chordates, 449 

 Prolactin, 73 



Pronephric duct, 777, 774, 775, 787 

 Pronephric kidney (pronephros), develop- 

 ment of, 774 



origin of in chick, 776 

 Proprioceptive field, 842 

 Prosencephalon, 812 

 Prospective fate, definition of, 379 

 Prospective potency, definition of, 379 

 Prostate gland, development of, 802 



function of, 31 



possible elaboration of fructose by, 34 

 Protective membranes, reproductive duct 

 as, 914 



types of, 901 

 Protein breakdown, products of, elimina- 

 tion of, 771 

 Protein synthesis, problematical, 159 

 Protoplasmic astrocytes, 810 

 Protopterus annectens, lungfish, xvi 



reproductive and urinary ducts of, 799 



skin of, 559 



stomach area of, 621 



terminal nerve (cranial n. o.) of, 827 

 Prototheria, xix 

 Proventriculus (glandular stomach) of 



chick. 623 

 Psalterium, of cow's stomach, 623 

 Pseudobranchus striatus, external gills of 



larval form, 640 

 Pseudopregnancy. 93 



Pseudo-vaginal birth canal, of the opos- 

 sum, 63 

 Pterygoid muscle, 717 

 Pterygotemporal muscle, 717 

 Pterylae, 573 

 Ptyalin, 617 



Puberal period, of post-embryonic devel- 

 opment, xiv 

 Pubis, 693 

 Puckett, W. O., 892 

 Pulmonary organs. 636 

 Pulmonary ridge. 869 

 Pulpy nucleus (Nucleus pulposus), 682 

 Purser, G. L., 197 

 Pyloric area, diverticula of, 601 

 Pyloric ceca, 601 

 Pyloric end. of stomach. 621 



Quill (calamus), of feather, 571 



