SECTIONAL TRANSACTIONS.—D. 451 
liver, the existence of a pair of hearts in the tail operated by extrimsic mus- 
culature connecting up the blood and lymphatic vascular systems, and the 
occurrence throughout the body generally of large ‘lymphatic’ sinuses, trunks, 
and vesseis which always contaim a percentage of red biood. Aithough it is 
often asserted that the presence of red blood in the lymphatics is due to acci- 
dental extravasation, it can be demonstrated beyond question that its occurrence 
there is a normal phenomenon. ‘his being so, it is obvious that there must be 
a regular circulation in the lymphatics, and it should be possible to show how 
red blood enters and leaves the so-called lymphatic system. As regards the 
latter point there are four definite places where the contents of the lymphatic 
spaces are directed by valved openings into veins : (1) the contents of the large 
subcutaneous sinus are drained by the caudal hearts and pumped into the 
caudal vein, whither they pass into the paired posterior cardinal veins; (2) the 
last or sixth pair of peribranchial sinuses discharge into the venous anastomosis 
between the right and left anterior cardinal veins immediately in front of the 
heart; (3) the lingual sinus discharges posteriorly into the inferior jugular 
vein; (4) each anterior cardinal vein is constituted in front by the union of a 
superficial and a deep factor; the former originates in the brain, but the 
latter arises directly and without the intervention of capillaries from the 
hypophysio-velar lymph sinus. 
In addition to these veno-lymphatics, however, a true lymphatic system, 
arising as blind capillaries and discharging into the venous system, can be 
established in Myxine. An undoubted lymphatic capillary plexus is found on 
the gall-bladder and everywhere in the wall of the gut. In the latter case it 
forms a typical and beautiful plexus of almost microscopic vessels lying super- 
ficially to the blood capillaries and discharging into a longitudinal lymphatic 
duct which accompanies the portal vein. At its two extremities and at intervals 
along its length this duct communicates with the sub-chordal lymphatic trunk, 
from which the lymph can enter the blood-stream by three routes via the caudal 
hearts. There is another elaborate plexus of, however, coarse lymphatic capil- 
laries on the surface of the ventricle of the heart. This plexus discharges into 
the lymph sinus which surrounds the ventral aorta, from which the lymph 
reaches the anterior cardinal veins via the peribranchial sinuses. A further 
coarse plexus is associated with the fin rays of the caudal fin. This opens 
into the subcutaneous sinus, and thus communicates with the caudal vein as 
already described. 
In addition to the system of lymphatic sinuses and ducts, there occurs also 
in Myxine a series of segmental lymphatic units which originate largely from 
capillaries in the somatic musculature. They differ from the segmental arteries 
and veins in that they course in contiguous pairs, which occur sometimes in most 
segments of the body and sometimes in alternate segments. They empty into 
a paired sub-chordal trunk which passes almost from one end of the body to the 
other. Each segmental lymphatic has a special connection with the e%tensive 
subcutaneous sinus, and its contents may reach the venous system by several 
routes. 
18. Prof. J. H. Asuworru, F.R.S.—The Life-history and Affinities 
of Rhinosporidium. 
Rhinosporidium secberi causes proliferation of the connective tissue and 
overlying epithelium, producing growths in the nose, conjunctiva, &c. Recorded 
from Argentina, India, and U.S.A. 
Earliest stages about 6 in diameter, spheroidal, with chitinoid envelope, 
vacuolated cytoplasm, and vesicular nucleus the chromatin of which is contained 
in the karyosome. Chiefly between or among connective-tissue cells. Granules of 
protein and fat globules soon begin to appear in cytoplasm, and increase until 
cell reaches a diameter of about 602, when chromatin issues from karyosome, 
four chromosomes are formed, and a spindle with centrosome at each pole, and 
mitosis takes place. Succeeding nuclear divisions result in formation of 4, 8, 16, 
32, and 64 nuclei. At each division the nuclei undergo synchronous mitosis. 
About the time of the seventh nuclear division (128 nuclei) the envelope becomes 
- much thickened by deposition of material indistinguishable from cellulose on its 
inner surface, except at one point where the future pore will be formed for 
escape of the spores. In sporangia with about 2,000 nuclei the cytoplasm begins 
