● Excretion is performed by `color{Violet}"Malpighian tubules"`.

● Each tubule is lined by `color{Violet}"glandular and ciliated cells"`.

● They absorb `color{Violet}"nitrogenous waste products"` and convert them into `color{Violet}"uric acid"` which is excreted out through the `color{Violet}"hindgut"`.

● Therefore, this insect is called `color{Violet}"uricotelic"`.

● In addition, the `color{Violet}"fat body"`, `color{Violet}"nephrocytes"` and `color{Violet}"urecose glands"` also help in excretion.

● The `color{Violet}"nervous system of cockroach"` consists of a series of `color{Brown}"fused, segmentally arranged ganglia"` joined by `color{Violet}"paired longitudinal connectives"` on the ventral side.

● `color{Violet}"Three ganglia"` lie in the thorax, and `color{Violet}"six"` in the abdomen.

● The nervous system of cockroach is `color{Violet}"spread throughout"` the body.

● The `color{Brown}"head"` holds a `color{Violet}"bit of a nervous system"` while the rest is situated along the `color{Violet}"ventral (belly-side)"` part of its body.

● It is the reason that if the `color{Brown}"head of a cockroach"` `color{Brown}"is cut off"`, it will `color{Violet}"still live"` for as long as `color{Violet}"one week"`.

● In the head region, the brain is represented by `color{Brown}"supra-oesophageal ganglion"` which supplies nerves to `color{Violet}"antennae and compound eyes"`.

● In cockroach, the `color{Brown}"sense organs"` are `color{Violet}"antennae"`, `color{Violet}"eyes"`, `color{Violet}"maxillary palps"`, `color{Violet}"labial palps"`, `color{Violet}"anal cerci"`, etc.

● The `color{Brown}"compound eyes"` are situated at the `color{Violet}"dorsal surface"` of the head.

● Each eye consists of about `color{Brown}"2000 hexagonal ommatidia"` (sing.: ommatidium).

● With the help of `color{Violet}"several ommatidia"`, a cockroach can receive `color{Violet}"several images of an object"`.

● This kind of vision is known as `color{Brown}"mosaic vision"` with `color{Violet}"more sensitivity"` but `color{Violet}"less resolution"`, being common during night (hence called `color{Brown}"nocturnal vision"`).