26 
MEMOIR OF SWAMMERDAM. 
drawing, afterwards published by Blasius ; and states 
the result of liis inquiries in a letter to Thevenot, in 
(he following particulars: 1. The Spinal Marrow 
consists entirely of fibres. 2. Those distinct fibres 
meet and terminate in some part of the brain. 
3. Fibrous nerves issue from the fibres of the spinal 
marrow. 4<, The pia mater is altogether extended 
into hollow sheaths. 5. All these things may be 
easily seen by suddenly placing the yet warm spinal 
marrow along with the vertebrae containing it in cold 
water, and breaking the vertebrae with great caution 
from the marrow', after having suffered both to re- 
main in that situation during the space of a day 
and a night. 
After composing an elaborate essay on Respiration 
as a thesis, he repaired to Leyden to take his degree. 
There he resumed his intimacy with the famous Van 
Horne, under wiiom he had formerly studied. Aw'are 
of his extraordinary skill in such matters, this Profes- 
sor engaged him in a variety of experiments, and in 
forming anatomical preparations, for which he took 
care to supply him with abundance of materials ; and 
with such enthusiasm did the young physician prose- 
cute this congenial task, that he is said to have 
laboured both by night and day. It w r as on this oc- 
casion that he first injected the uterine vessels of a 
human subject with a ceraceous matter, a useful 
operation w r hich he subsequently learned to perform 
with great accuracy and beauty. He now r also be- 
gan to practice a new and excellent method of pre- 
paring delicate viscera for demonstrations, namely. 
