492 Simon Henry Gage 



A. Red blood-corpuscles of the lake lampre}'. a, face view of a cor- 

 puscle ; b, optical section of a corpuscle on edge ; c, face view of a cor- 

 puscle, showing the nucleus after the action of one per cent, acetic 

 acid ; d, cup shaped corpuscle. 



B. Red Vjlood-corpuscles of the brook lamprey, a, b, c, the same as 

 in A. 



C. Red blood-corpuscles of a larval lamprey 142, mm. long, a, b, c, 

 as in A. 



D. Red blood-corpuscles of a larval or embryo lamprey, 9 mm. long. 

 a, b, c, the same as in A. 



E. Rouleaux of the corpuscles of the brook lamprey in optical sec- 

 tion. In the lower corpuscle a nucleus is indicated to show that it is 

 small and in the thickest part of the corpuscle. It is visible only after 

 the hemoglobin is partly or wholly removed from the corpuscle. In the 

 embryo, where the corpuscles are so small, the nucleus is faintly visi- 

 ble in many corpuscles before the removal of the hemoglobin. 



F. Rouleaux of the 142 mm. larva focused on the upper surface. In 

 both E. and F. the corpuscles are shown of different sizes. Compare 

 the maximum and minimum diameters in the table of measurements. 



Fig. 43. (X about 1000). A single white blood-corpuscle in various 

 amoeboid phases, drawn freehand within two minutes. 



Fig. 44. (X about 1000). Fibrin filaments of a larval lamprey. The 

 filaments seem to radiate from centers, the centers appearing like white 

 blood-corpuscles. Some of the filaments are moderately coarse, others 

 exceedingly fine. c. a red blood-corpuscle with eccentric nucleus. 



Fig. 45. (X about 1000). Human blood fibrin, to show the coarse- 

 ness of the filaments and also centers of radiation, c. A red corpuscle 

 drawn at the same scale. 



Fig. 46. (X 700). Zoosperms of a lake lamprey. Three are shown 

 entire. On each is a bulbous termination of the tail, and in the one at 

 the right is an enlargement of the tail near the tip. 



A. Two heads (X 2750). In the one at the right are shown two 

 clear highly refractive bodies. 



Fig. 47. Zoosperms of the sea lamprey. A single zoosperm drawn 

 entire and magnified 700 diameters. 



A. A head and the bulbous termination of the tail (X 2750.) 



Fig. 48. Zoosperms of the brook lamprey. Two entire ones are 

 shown at a magnification of 700. The tail of the one at the right is 

 nearly uniform and ends in a point. The one at the left ends by a little 

 knob as with the lake and sea lamprey. 



A. Two heads magnified 2750 diameters. 



Fig. 49. (Natural size). A glass vessel containing sand and water 

 with a larval lamprey in its burrow, to show the position naturally as- 

 sumed by the larvae. 



Fig. 50. (X 3). Head of a lake lamprey in the transforming stage to 

 show the narrowed head and the snow white pineal eye. 



I, 2. The first two branchiopores. dc. Posterior dorsal cartilage. 



epi. Epiphysis or pineal eye surrounded by a light area. 



n. Nostril with the opening directed obliquely cephalad 



Fig. 51. Oblique view of the head and branchial region of an adult 

 lamprey showing the direction of the expiratory currents from the 

 branchiae and from the nasal sac. 



bp. The branchiopores. 



n. Nostril pointing obliquely cephalad. 



